Correct. Mena was not meant for being Heir. While she's technically been Heir longer than Draken was, it's always been an uncomfortable weight on her.
Furthermore, Stephan has been handling the drastic repair and resettlement of his province. Make no mistake. The damages that Ostland suffered in the Vampire War are not comparable to what Nordland suffered. Population cuts are one thing, sure, 1/2 surviving vs. 1/3 surviving respectively, but Nordland lost Salzenmund compared to Wulfenburg only suffering the one extremely personal incursion. Furthermore, Zacharias was scattered as hell, and had no major focus to his warmaking. He demanded attacks on places that weren't there, or had moved, or had never existed. His command style was incredibly decentralized, with sub-commander necromancers and vampires basically just rampaging and wandering about due to fear of Zacharias if they didn't. Gruber, on the other hand, corrupted much of the provincial nobility and state troops, knew the state of the province like the back of his hand, corrupted significant areas to the point that it was the effort of many, many years by the Cult of Shallya and the Elves of Laurelorn to cleanse them enough for habitation and usage again, and outright eradicated a lot of infrastructure in preparation for a Materium expansion of Nurgle's Garden.
The issue with this massive long-term rebuilding is that it is boring and expensive, and if there's one thing that a heavily half-Norscan blooded Ulrican nobility might get frustrated with, it's boring and expensive. It's not 'sexy' or 'prestigious' to spend thousands of gold crowns to section out, re-till, and re-plant fields, or create towns from the ground up and slowly shuffle the people in measured fashion to resettle areas, wait for new births and buildup, and then do it again. His armies are carefully deployed and largely patrol back and forth. This is also discussed in the aforementioned Trident Meeting that focused on Mena, Reinhardt, and Magnus. Stephan does not have the same sheer prestige score that Frederick does. He was not invited to Karak Ungor, he accomplished no staggering incredible deeds at the Battle of Three Armies, he did not throw his armies at Sylvania and have them emerge with a victorious heroic legend beginning to be built around a unique individual such as a loyal ogre/elf/dwarf/halfling/whatever and his children are mostly quiet and industrious in following along with his own course - aside from Mena, who has ever chaffed at the role she's been forced into, and Draken, who resents his very existence and birth and outright hates his parents for 'tricking' him into believing he could have a 'normal' life. He has neither offended the Gods nor been granted salvation by them, no pyre was set for him that did not burn because he has committed no heresy, and he has never been keelhauled because he has ever been deferent to Manann - he set up his new temporary capital on the island named for Manann, for goodness sake.
Fredericks' prestige score, it bears repeating, means that he is able to get away with a lot more. By weight of reputation and connection he can, generally, be seen as able to crush local issues underfoot without even necessarily noticing by certain parties. Stephan does not have this luxury of perception, for all that Frederick bought it with sheer blood and pain.
However.
The unyielding steel core of the man who saved 1/3 of the province from Gruber when the world seemed to go mad, who suffered a childhood and early life of mockery, hatred, and self-loathing for the crimes of his parents, who was branded as a babe with the Mark of Chaos thanks to the machinations of Gruber in ruining his family, who held out in a merciless multi-month siege as the very land all around them was warped by Nurgle, who refused to yield despite nightmares and darkest sorceries assaulting his mind and soul nightly, who was prepared to ride out against Gruber after Frederick arrived despite levels of starvation and sleeplessness that would kill some lesser men? He's still there.
That man is not yet dead.
The problem is that it has been decades since the province has been reminded just who Stephan the Unbroken is, and as such, after years of Mena letting her husband, her father, and her siblings deal with matters at court, Mena's position at court is intensely unstable and unwell. The fight in Ostland was meant to be her last hurrah, a gift of bloodshed and pious war in the name of the Gods, before she gave up the Blue Wolves and went to fight not with steel but with words, given to her by Magnus, with Reinhardt there to show his support both for Mena and Magnus and Ostland as well. They simply happened to finish with critical potency far ahead of 'schedule', and for this, there was guilt, there was self-recrimination, there was maudlin disappointment. Then they got to drinking, and then through the depths of that drinking, there was an option, a possibility, a desire to give comfort to a friend in the way that she favored most - before she resigned herself to truly living the life she never wanted but duty not compels her to.
Thus, Albion. I'm tired and don't care to go back, but I recall...wish fulfillment, or something, being accused of with regards to what's happening. No. 'Wish fulfillment' would be the Polar Gates closing once more, disease being eradicated fully, the insanely harsh nature of the Empire wearing away, and only glory and kindness and peace for all. The greenskins and skaven would cease to be, the Druchii cast down, and there would not be a woman suffering a near heart attack every time her husband went to fight. Or a young woman who couldn't simply ride and be free upon the roads and plains. And I could write that. It would be all of 100 words, at most. And I suppose that could be the 'end' of any and all writing in this quest, in this universe, because what else would there be? This is friendship taken to extremes in a world of extremes, lubricated with a bit of extreme chance, and a bit of extreme alcohol, and a slight push of fate to go to somewhere and fight some things and do some stuff. And really, that's basically Warhammer in a nutshell. When Gotrek and Felix popped out in Albion, it was because that's where they ended up. The Heir Group could have ended up in Norsca, or in the Wasteland, or just in Troll Country, the point was to go try and fight something to fight something because all of the 'major' fighting in Ostland was done so early. It was literally a four sided die. At this point I'm rambling, bleh. Night ya'll.