Thank you for playing and for so detailed review.
About the boss. I understand what you are talking about, mostly. I would say that Sekiro bosses also ignore your attacks, and do whatever they want most of the time. It feels better in Sekiro cuz there is "fixed" distance between you and the boss, that when you got hit you get pushed on length for next boss hit and when you hit boss get pushed. This aspect I completely forgot and, to be honest, had no time to focus. Another mistake that I made enemy parry drop your stamina bar very fast. You can't really adapt to it. And attack animations that I have very fast, almost without a build up. Unfortunately, I don't have skill and tech to make unique animations that will be more suitable for this kinda game.
Immerred can't deal damage to you when you parry her tho. When she hit you, doesn't matter if you block/dodge/parry/received it this attack sequence goes into timeout until animation reaches a frame where this resets. You can argue that resets happened very often but you are 100% can parry all the attacks.
I 100% failed with Otomo wave attack. I didn't manage to sync VFX and collision. It can be parried tho. I thought that sound cue when Immerred says "For Justice" would be enough to parry. It seems music little loud and people just don't notice it.
About level design. In second level particularly I put most work. There several paths to complete this level. Some path include ridiculous amount of enemies but it was done with purpose to show the player don't go that way. It's a bad way. About bullet hell, I decided it's funny if you ignore everybody, so i just left it be :D
Bugs that you mentioned, I tracked them but I was a little bit burned out to fix them in the grace period. My bad. I don't know if I will support game post Jam. I have other long term project that I want to focus more.