Yeah, totally understandable! I think I'm kinder to CS2 than you but I get where you're coming from. They were definitely in a complicated situation with that story because it's wayyyy too long to make as a single game (both in terms of dev cycles and for players), but splitting it into two meant it was going to be impossible to avoid the completely different pacing across both games, and even then both of them feel like their endings drag on for too long after their respective climaxes. The final final dungeon of CS2 (in the epilogue, not the finale) really had no place being anything but an optional post-game dungeon imo.
I didn't really mind the revisiting, personally, especially because it comes with interesting character growth even if there's no huge plot differences. And everything with finding the scattered students I really enjoyed after having seen all their little individual arcs in the first game. There's definitely a weird amount that happens offscreen, but on the other hand I'm not sure it would've really worked with the tone to just outright have a lot more involved war sequences.
I'm actually really curious to try CS3 for that reason (among others - I also just want to keep going haha), but given what I've heard about its contents I've started going through Trails in the Sky first (and might get around to Zero/Azure first too?) so I can have any context whatsoever for a good chunk of the cast. It's going a little slow since I'm following a guide to avoid missing things, but it's really neat to play after having seen CS. Especially all the comments everyone makes about how Erebonia is the worst place ever lmao, I know, I've been there.
And yeah, I love a lot of the epilogue/divertissement in theory, but in practice the execution just really really drags, especially when the epilogue dungeon is significantly less interesting and less relevant than the finale dungeon. I also wasn't super fond of the divertissement dungeon but I think that one's more a matter of taste.