Welp, I think I'll make a wordwall about this too. No promises that it'll be entirely on point, I'm still kind of sleepy.
I think first I would like to brown townyse the political makeup of the three confederations surrounding us. You had mentioned before that they were similar to the German Confederation, which was made up of lots of small states, who were constantly bickering and looking to expand their own lots in life. It would be reasonable to assume that our three confederations are looking to do the same.
Now, I think what is throwing me, at least, for a loop is that the entities that make up the Confederation are called "tribes", yet they exist in the first world. For me, it makes me assume that they are smaller and less organized than perhaps a citystate or territory or simply another nation.
I think I'll elaborate a little further on what I would think these Confederations would be doing; many of them share separate interests, and really they would only be held together by their supposed foreign invaders. After Obalei surrendered, you have got to imagine that the governing bodies for both confederations would have gone into turmoil; they had just lost 33% of their support, and now the UEK would be able to turn their full attention to fighting them. Not only that, but especially for the Tacz, they would be trapped in a two front war. The clear option, and the option they took, would be to request peace, obviously. How would that decision affect the governing bodies? I'm sure many would be scared of further war, or perhaps angry that other tribes would have even suggested an end to the fighting.
Now imagine what happens when their peace offer is declined and a new offer is proposed; annexation, but with respect to the current governing establishments, allowing those in power before to remain, or total annihilation and the forced annexation and replacement governments. What would the two councils think now? A large portion of them had wanted peace, and the offer mentions that. Accepting peace would allow them to remain with all the power they had before, only having to accept the Kyrevan king and his laws and money. I'm not assuming that all of the tribes that make up this confederation would agree, but I would assume that at least a few would, and if not that, at least some of them would become neutral, similar to what happened in the Americas during French and British colonization.
My suggested result: Several tribes from Noaste and Tacz leave the Confederation and either become neutral or side with the UEK or Kyrev in the conflict.
I'd like to discuss the UEK's internal situation as well. Now, don't get me wrong; they have just devoted an enormous portion of their able bodied men to a conflict, and that would have repercussions at home. Additionally, there would be problems with supplying them all with muskets, for example; HOWEVER, I think we're skipping over a couple important factors that would influence this. For one, many of these men lived in the mountains or around them as frontiersmen; it could be assumed that many had their own muskets or weapons. Additionally, at this time a majority of a nation's populace would be farmers; if I remember correctly, we're approaching winter, so most if not all crops would be harvested. While I'm not saying that it would have no effects, most of the farmers would be able to leave without much issue. Now, they would also be pulled from the industrial and skilled trades market, which would be partially crippled until these men returned home. However, at this time the industrial market is not nearly as important enough at this time to cripple an entire nation, and the skilled trades market could be reasonably assumed to remain whimpering at the very least. I'm not debating the fact that this would make the UEK's population as a whole very unhappy, but nation-wide revolts only a few weeks to a month or two after they are conscripted is unlikely in my mind.
My suggested result: UEK's internal strife grows, and the longer that troops are kept away from home, the larger the strife will become, eventually turning into full scale revolt.
This is all speculation, of course. Do what you will, but this is my opinion.