The Beast Cowers works to intimidate anything according to its description, its just especially effective against beasts, and as said, we have traits that would make it especially effective against non beasts anyway.
If causing fear is all we want, then there are other spells that do the same and arguably do it better. And I already made a case for why it's probably not as helpful on this particular campaign as the description suggests.
Added to that is spending our slots right now on spells like Breath Fire and Rock Blast just seems like kind of a waste. We know Aethyric Bolt, we just bought a gun so we can save ourself the need of using low level blasto magic, it seems a waste to spend then multiple action slots on blasto magics like that.
It was explicitly mentioned that AB has a different form and function than BR/RB. You were quoted directly in that statement. And the pistol fills the same niche that AB does (we got it primarily because it's not a spell), which means that BR/RB still cover some distinct holes that both AB and the pistol leave wide open. Which also doesn't touch on the general utility of a mid-tier AoE fire spell, which while its primary purpose is burning enemies can also be used for other things AB can't.
So no, there is no scenario where having Breathe Fire is a waste. Maybe a bit obsolescent in the extremely specific moment where the
only thing you want is to snipe a single heavily armored target, but not a waste.
Honestly, and no offense, but this seems like a terrible plan. Leaving aside that learning five spells here means a not inconsiderable action investment in teaching the guy chemistry, we already have a backlog of two things we can write papers on which we haven't yet. We don't lack for subjects to write papers right on right now so much as we lack for high quality ones that will wow the tower, and judging by how much disdain Fanriel herself views elementalism is it isn't likely to be that high quality paper, to the point we'd be better off just using those actions to write the papers on the subjects we do have available right now.
Dampward is a spell that I might have considered if it wasn't that the only armies that make frequent use of gunpowder where we operate are the Empire, Dwarfs and to a much lesser extent Kislev, which are not exactly going to be our most common enemies. Chaos and Greenskins in contrast make little to no use of it.
Right this very instant, Finreir (I think that's his name) is arguing with the Elves that humans need more respect. It was in an earlier update.
The more papers we publish about the potential uses of human knowledge (and more importantly, how these can serve High Elf interests), the more ammunition he and his supporters get to assist the Empire and Kislev when the great war kicks off. Which, even if that's just one other mage turning the canon three into four, is a significant boon to the people hiring us in general, which increases our chances of survival, and increases the chances of all of them making it back home again.
And if you can present a feasible plan for when and where we will get the chance for another exchange like this, I'll be happy to consider paring it down. Until then, 5 actions for a single turn is a notable but not a huge imposition on us when we're still a tiny merc company.
Dampward is an AoE anti-fire defense in addition to anti-gunpowder, and also has potential as a debuff in Fanriel's hands - high humidity is hard on those who have to breathe. Although it's not been tested, I can also see it as being an anti-gas attack, cast it when spores or poison mist are used to bind water to them and make them spread less.
There are a lot of useful details you're not addressing in your argument.