We also have a bit of a sore spot whit brettonia for not joining when they could.
Ngl, for me it's less that they didn't join, and more how they went about it.
When we were deciding where to base the project:
Our Grey colleagues: "Here's a list of pros and cons for places nearby. Can't win them all, but you'll be in a different position depending on where you go."
Laurelorn: "Oh sure, we'd be glad to house you! A great old library would be yours to peruse, and millennia old elf scientists will help you out! Sadly, this all would be hard to arrange if you choose a different place..."
Boris: "Push back Chaos? I'll move mountains to make it so! Although I don't think you'll care much about helping Kislev if you base the project away from the frontline. Nobody does."
Bretonnia: "One of the Fay Enchantress's most trusted helpers will give you pointers. But if you decide to base your project elsewhere, we're not sure our hearts will recover from being snubbed so </3"
like cmon
later on, when most people we asked to join went "That's a troublesome thing you're asking for. I'd need some of my own troubles dealt with before I can help you" and Mathilde was like "okay what's your price" and that was that, the Bretonnians she talked to did a weird social dance, and then said something to the effect of "we don't feel like helping you. on unrelated note, there's something we don't need help with because we're so chivalrous" and like the
subtext was the exact same, in both cases, but it just feels so obnoxious. Idk if it's just me.
TL;DR: Bretonnians didn't refuse to do anything, they offered the same general kinda deals as everyone else (and Mathilde had no trouble at all parsing what they meant), but the way they phrased things was grating to me and that's why I don't want them in the project.