1 - I will have that fixed!
2 - I will also have that fixed. I mixed a few switches (conditions) up with those ones. I thought I fixed them the first time around, but I guess not.
3 - I will turn up the odds of them using it since I was also having a hard time getting one to trigger once.
Edit: The player will have to fight regardless of getting all three boxes, this boss is just messing with you and wasn't actually planning on letting you leave alive. That is why I left a crystal around the exit in case if the player cannot beat them or gets stuck. Getting the boxes just determines if you fight them enraged or not.
4 - Honestly, I have no idea why RPG Maker does this with these tiles in specific despite setting them as unwalkable. (I to fix that I am going to place invisible barriers using events like I did in the second chapters super boss dungeon with the puzzles and the altars since they had the same issue)
5 - As far as I am aware, the damage shouldn't be a thing from the new revival spell. It may however be one of two things (maybe both) which is that if you are fighting in the water, if an ally that isn't aquatic (or has no lungs like the gold monsters to drown with) then you will need to reapply the water breathing potion or else they start to drown which could cause that damage, the other possibility is that the parasite enemy has a chance to poison you with each attack. (I think it may be one of those since you claim to be fighting parasites, which means you are underwater and could be drowning. To get rid of the drowning effect all you need to do is reapply to water potion. If it persists, then I will take another look and make more guesses as to what it could be).
Edit: Fixed in the next update, since I started on the next one.