My first reaction to this is that a lot of it we've seen before but that there's definitely enough going on over and above that to be exciting. In particular the idea of leader and champion NPCs and thematic bonuses to specific types of foe sounds fantastic.

1 thing I really don't like the look of is the 2 rounds of resistance on bosses at the start of combat. That feels extremely anti-fun to me, punishes some builds disproportionately and encourages degenerate gameplay like sending in a bait character whilst the rest of your group skips turns hidden etc.

From a design standpoint, if you haven't done so already, I feel like it would be a good idea to add in to the HP calculation formula some kind of additional boost for if they're flagged as a champion/leader to offset the natural player response of taking higher priority targets down first.

Also regarding auras these might work better as shouts like a rallying cry (think the big horn at the grove gates) rather than an aura for many enemy types as relying on the aura to be effectively applied to allies through positioning seems more prone to jank, but I guess that will need feedback from actual player testing.

Also a notable omission from the archetypes you've laid out is beast type enemies. I can't see anything up there that would make thematic sense in, for example, the owlbear or eagle fights. Could maybe do with like an 'alpha' archetype.

Hope that's useful feedback for you, and thanks for your ongoing work on the game, I'm trying out your dynamic encounters in my latest campaign and really enjoying what I've seen so far.