After the battle where all your cap mages suicidally creamed all my non-chaff eastern forces, if you had pushed forward with what you had securing your border I'd have folded. Or just as much to the point, if Mari or Agartha or Oceania had pushed then, I'd have folded. If two nations had ever pushed at once, I'd have folded. The elephants in the room, Arco (who was never at war with BL, mind you), could have pushed forward alone any time they pleased, and it would have been ugly, but they would have won. They didn't, obviously, because they were weaker against non-Ermorian armies like you or Mari or Agartha at that point, while they could definitely smash anything less than an all-out offensive from me (and probably could smash that too, albeit at greater cost). So better to sit by passively keeping me from doing anything but turtling while they got to the late game with a huge swathe of territory, lots of gems, elemental royalty, etc. Congrats, we're there. They're almost certainly going to win because they played the anti-Ermor diplomatic game perfectly.
Ulm lost, but to diplomacy, not geography. Having 7 0-pop provinces to your north - of which you might get half - will never matter as much as the 30-or-so full-pop provinces to your east that you'll never hold because of Arco. Arco is probably not stoppable barring a a prompt dogpile coupled with some serious late-game shenanigans, and I don't see that happening. Not my problem, though. I've been warning against that for years in-game, and no one cared. So, you're welcome to it; maybe you all can transition well enough to beat them. I doubt it, but maybe.
[Point of reference, since it doesn't matter at this point: my research is 3/5/5/4/5/5/5. This is the threat to all life you're still railing on against.]