I find that the volcano dungeon is WAY to hard, so I have a few suggestions to make it a bit easier.
1: reduce the amount of bees/wasps in the vault room
2: reduce the amount of armored crabs in the sorta maze part
3: add a stuffing machine in the tiny room before the vault (so it's not almost impossible if you don't have pillow plants)
That's kinda it, I mean you could maybe add a teleporter in the vault so you don't have to backtrack but I think that that would make it a little too easy.