Love to see that this got finished! Had a good time playing through it all.
But, so you're aware, here's a number of bugs I've encountered:
The Explosive Revenge perk causes most enemies to just lose the ability to move and get stuck in place. Amusingly, using Spectral Freeze on the stuck enemies will make them slowly move backwards until the slowdown effect wears off, where they then just freeze in place again. (Speculation, possibly the movement speed of the enemies gets set to 0, and then spectral freeze subtracts some from that making it negative causing them to go backwards?)
Enemies quite frequently spawn too close to the walls and just become stuck. This one's been around for a while. I also had one instance of a single enemy spawning completely out of bounds.
Serpent boss in Zone 1 is broken and doesn't open the exit portal, but you seem aware of that based on other comments. During it I also had an oddity where I leveled up in the middle of the fight and was forced to choose a perk immediately instead of waiting until the end.
Gallery of Gulps didn't open up after beating the final boss
Closing and reopening the game after beating the final boss and getting the true ending allowed me to select Continue Delve again, which put me at the final boss while at level 1 without any perks or breath abilities. Exiting the battle disables the button again. Honestly this one's kind of an amusing challenge to have and makes me wish for a way to refight bosses after they've been beaten once without having to go through the whole game again (though probably with appropriate gear rather than with literally nothing but the bite lol). Doing the same after the bad ending instead just put me back at the choicer for which bad ending to get.
Pausing and unpausing the game during the final boss causes the health bar to move up the screen (only discovered this while doing the no perks/levels refight from the previous bug). Doing it enough causes the health bar to disappear off the top entirely
And that's it for the notable bugs I remember. Couple more things, I'm curious where the music is from since I especially liked the final boss song, I'd be happy to listen to it outside of the game. And, I don't know if you plan on updating this game any more outside of bug fixes, but if I may make a small request, I think it'd be fun if the true ending had a small bonus vore scene between Kram and Saphra, one where they can reform unlike the bad ending.