Not as frustrating as the game-breaking bugs. I counted 4 of them, 2 are very serious.
I admit that the evil route is a lot less tested than the good one. For the good route I had several people testing it, while for the evil route it was just me. There likely were some interactions I missed because I only played two or three evil playthroughs. Different people would make different choices and I couldn't cover them all.
I would love to go back to fix the bugs that are still there, but unfortunately I lost the development files a long time ago. For every fix I make I have to de-compile the game, take the broken parts into a 'clean' project. Then, once done, I have to overwrite files with the fixed versions hoping I don't break anything else, it's not unlikely some of these bugs appeared as a result of me doing just that.
At least the game is beatable. 1 of the bugs is present in any playthrough though. In Gaia's flashback if you save in the bathroom - you're not getting out. The cutscene activates after opening the door. After saving it resets for some reason, so after trying to open the door from the inside - Gaia gets in the water and doesn't get out even after the end of the cutscene. You can only change direction, but movement is impossible.