Yep, arrows do go through walls! The only issue I was questioning is hitting an enemy and, well, not hitting it, that's something I don't think I've ever had issues with. Sorry for not being clear enough here.
The other concern both comments mention is the timing of some attacks, specifically with Lady Fin's tail swing, that definitely needs some preparational move or something to let the player know it's even happening before they get yanked.
Pufferfish put clouds of poison next to the player, but if you're standing still while they do it you won't get hurt, so they're sort of annoying little minelayers. We might want to change that (while decreasing their damage because they really hurt now if you aren't careful).
To sum up, the combat is raw and that's something we're working on and will patch after the jam ends (sort of unfair to do so before that, we had a month like everyone else, and a deadline is a deadline). That said, it's only 2 weeks, so that's about the time it would take to properly tune all that stuff anyway.