What makes a dark age a dark age? Misery, squalor, mass deaths, widespread illiteracy, technological backsliding, cultural stagnation? Well, that's how it's generally understood, but that's actually a mash-up of three different but overlapping meanings applied by different people with different motives. In the sense most used now, the colloquial sense, it's the low point in the story arc of a nation or people or continent, the second-act nadir that the protagonists must recover from. I've referred to the history of Kislev from shortly after the Great War to approximately nowish as a dark age, and the entire Time of Three Emperors as a dark age, and the Time of Woes is often referred to as a dark age. So far, so good, but there's a couple of significant problems with this.
First, history is very rarely so neat. Centuries of the history of a country or an entire continent cannot be as neatly summed up as that bit with Frodo and Sam in the ruins of Osgiliath. But once you've got the hammer of a historical template, an awful lot of things start looking like nails. Were there lucid moments of the Vampire Tzarina's reign? Were there periods of relative peace in the Time of Three Emperors? Were there lulls in the miseries of the Time of Woes? Have all of those been flattened under the dark age steamroller?
Second, just because it's the most common meaning doesn't mean it's the only one, but it's often assumed to be. Because when something is referred to as a dark age, most people assume they mean this first meaning, when it can actually mean one of the other meanings I'm about to get to. There's a reason why very few people use the term 'dark age' any more, and those that are too insistent on doing so should be very seriously side-eyed. There's a reason why you generally hear the terms 'Middle Ages' or 'Medieval' used instead today, and there's a similar shift happening in discussions about the Greek dark age.
The next most common meaning is much more literal - it's a dark age because we can't see it. Written records are fragile, and for us to have enough written records of an era for us to feel like we have a good handle on what was going on during it, an era needs to have produced a lot of writing. The 'dark age' following the collapse of Rome was dark because it shifted the chunks of Europe that English-speaking historians tend to focus on from a lot of centralized bureaucracy with a highly literate upper class, to more local powers that had much less need to write things down and often under the leadership of Celtic or Germanic peoples who had a lot less tradition of literacy at the time. This is intended, but very often not taken, as a values-neutral descriptor. We're just measuring whether or not they created a lot of writings for future historians to find, we're not weighing in on all that human suffering no longer being created to glorify the senate and people of Rome.
(By this definition, the Viking Age could be considered a dark age, because the Norsemen didn't use writing in the way most socities we're familiar with did - they used it on monuments to record great people or deeds, and seemingly to label objects with what they were for good luck - perhaps to remind them what they were supposed to be doing? - but not to keep records about their society or their culture or their religion. It's a topic of much consternation that the main sources we have about the Norse religion weren't written by people that actually believed in them, but by their Christian descendants who had their own agendas and preconceptions and religious obligations. This sort of cultural pollution between us and the 'dark age' is what gets Loki depicted as a Satanic figure instead of as a classical trickster in some places.)
(...the modern mainstream understanding of Satan, that is. You could draw some fascinating parallels between Loki, who causes Odin's most annoying problems but solves his otherwise unsolvable ones, and, say, the Judaic depictions that have him as God's enforcer or designated naysayer, or that one biblical one making a bet about that poor bugger Job, or the Gnostic ones that have him as a righteous rebel against a tyrant, or Milton's sexy tragic rebel trying to do his best but doomed by his flaws, or the sulkily gorgeous omnisexual menace from DC Comics and then the TV show Lucifer. If you were looking for a topic for your thesis and/or historical or urban fantasy series and don't mind a little excommunication between friends you could go a step further and posit a common mythological ancestor for all 'trickster' archetypes and even all 'formally loyal servant of the head god that now rebels for some good reasons and some personality flaw reasons' archetypes.)
(Going back to before the Viking and Satan asides, these differing interpretations of the term 'dark age' interacts interestingly in 40k's 'Dark Age of Technology'. At first read with the first meaning in mind, it's a darkly ironic title loaded with the baggage of the Machine Cult - they consider an age of boundless technology and widespread peace and prosperity a 'dark age' because it does not align with their dogma, right? But it's a dark age in the second sense because in an age of so much technology, all the records were made with technology, and in an era after the AI revolt, all of that technology is destroyed or hostile, making all those records inaccessible and therefore the era is imperceivable. The third meaning ties into it too.)
The third and original meaning is pure propaganda. The dark age started when our ancestors stopped being in charge, and resumed when we got to be in charge again. The 'Renaissance' was first called the renascita approximately thirty seconds after the first smug Italian man put paint on his brush, and thirty seconds after that they were excitedly inventing new ways for yesterday to have been horrible to make today look even better in contrast, and thirty seconds after that every other country in Europe was adopting local variations on the tale, including a whole bunch of English historians that eagerly poisoned the well for the glory of Britannica, several Georges, and one Victoria. The overwhelming majority of 'medieval torture devices' you can find a million books and articles and youtube videos about were invented as a result of, and to further feed into, this dynamic. As was a lot of the reputation of the Inquisition. Don't get me wrong, they were horrific bastards, but they spent the overwhelming majority of their time being horrific in the context of religious persecution, which these eras were still largely in favour of. So the later stories of them pursuing literal and figurative witch hunts were largely invented, even though the doctrine of most of the organizations that could be called the Inquisition considered believing in the very existence of witchcraft heretical.
The relevance of all this to the topic at hand is that the Dwarves barely had one and didn't at all have the other two. The Time of Woes was bad, sure, but it was very binary - Holds either fell or they didn't, and the ones that didn't were more often strengthened by the influx of refugees than they were weakened by the overall experience. The Karaz Ankor overall could be considered to have had a Dark Age, but the only individual Hold that could really claim to have had one is Karak Azul from its period of isolation. The rest either ended or were fine. In the second sense, none of them should have had any discontinuity of written records. There's a line in Dwarven history about 'the Great Book of Grudges of Karaz-a-Karak falling silent during this period', but, uh, what? Are you saying there's no Grudge recorded for Karak Ungor? For Karak Varn? For Eight Peaks and its neighbours? Bullshit. Lazy writers just want to be ambiguous about ancient history and don't like people rightfully pointing out that the Dwarves should be able to tell you what Snorri Whitebeard had for breakfast on any given day of his life after half an hour in what surely must be their meticulously-index archives. And the third? Nah. The Age of Reckoning is at best referred to as a throwback to the glory days, not - never - an eclipsing of them. That just doesn't fit with the entire Dwarven mindset.
All this to say, where would linguistic drift even come from?
They live in the same places, peopled by the same peoples, ruled by the same dynasties, with unbroken chain of written records going back to the creation of their language, with ironclad cultural and religious doctrines saying that these cannot be improved upon and should not be deviated from. They haven't been conquered, they haven't been displaced, they haven't been abandoned and rebuilt, they've never been under foreign rule, they've never had a ruler from an alien culture inherit through come quirk of a gnarled family tree. There have been diaspora but they've all gone outwards. The Hill Dwarves, those that built settlements in the flatlands to trade with the Elves? Absolutely could have introduced linguistic deviation... except they didn't come back home, they stayed behind and became the Imperial Dwarves. Ekrund, isolated in the Dragonback Mountains for so long? They helped found Karak Norn. The Middle Mountains Dwarves only sent their least influential mouths to feed back to the Karaz Ankor. The Norse Dwarves definitely had a lot of cultural interchange with the Norscans, but never reconnected with the Karaz Ankor to feed that back into the mainstream culture. The Chaos Dwarves absolutely did, but they have more cultural influence on Orcs and Kurgans than they do the Karaz Ankor. The only significant population I can think of that was isolated for long enough to start veering onto its own cultural course and then returned to the imperial core were the Mountains of Mourn colonies.
By all logic, Khazalid should follow its supposedly ironclad rules a lot more than it actually does. This would be interesting, because it would be a point where they are completely alien from the 'rules' of culture and society that we are familiar with, a string for the curious to pull on that will lead them deeper into investigating these people. Or, alternately, each time there's a variation from these rules, there should be the clear fingerprints of the ones that did it, with footprints leading back to one of these fracture points in Dwarven history - another string to pull on. 'Dawongr' should have a paragraph about how it was reintroduced to mainstream Khazalid from Norse Khazalid from, I don't know, some early pre-Chaos Norscan (Norsii, back then) who saved the life of a Norse Dwarf King and the saga of their bromance got popular enough in the vacuum before the arrival of the Imperial Tribes that the Norse Dwarf word 'Dawongr' took the place of the original 'Dawongi'. It gives you a string to pull about Norscan history for free, too! Or you could have all these variations be the effect of a rising cultural influence within the Karaz Ankor of the Young Holds, adding an extra dimension to the cultural rift between the Old and Young that might make for a really interesting dynamic between the Dwarfier Dwarfs that are richer and wiser but a pain to get along with, and the less Dwarfy Dwarfs that don't have the bottomless vaults or the fanciest runes but might actually speak your language and won't cut off business with your family for ten generations if you forget the proper way to groom your beard before a formal meeting.
But the cost of doing that means you have to do that. You lose the throwaway jokes like 'bugrit' being a Khazalid word, which wouldn't fuss me but some people do like. You can't do cute little references and directly transplant Tolkien place names. You have to do something about all the grandfathered term from the early days of the setting. You have to reign in all the Black Library writers who barely skim the setting bible and have historically been given free rein to multilaser and Egrimm van Horstmann all over the goddamn place. Maybe you just plain can't do this sort of thing in a setting like Warhammer, a collaboration between thousands of people over forty years and counting. Maybe this is the sort of thing you can only manage with a singular word nerd with a singular vision at the middle of it, either a solo project or a sufficiently stubborn auteur. But man, to me (perhaps not the most unbiased perspective the world has ever produced) it really feels like a missed opportunity.
Actually, you know what? On further thought, I retract that charitability. They're basically rebooting the setting, they absolutely could chisel the rules into rock and bring the language into line if they had the stones. I came up with a lore explanation for Cor Dum even though it ended up being a stupid wiki typo, they can come up with one for dawongr.
