A bug can be anything that deviates from the expected result, such as an attack that is stated to one shot a boss and doesn't.
I'd also consider the image positioning a sort of bug since it is immersion breaking.
The up arrow shows up in the first part of the game, but nothing tells the player that they can't select it or why. (In other places, it looks like the up arrow would at least tell you what is wrong). I'd consider that a bug since it should at least give you some sort of feedback, like you searched for a path, but couldn't find any or such.
Not sure if the broken drum (or the trash pile) would count as a bug that you can walk on it, but it does look weird.
Clarity (Wording) I wouldn't count as a bug, nor would I consider battle balancing. I'd consider them things to fix though. Typos I'd consider a minor bug (they aren't usually that important unless your game is story heavy).
As an aside, I'd actually recommend you check out my recent tips stream to see how I had escape sequences. It is a bit more work (if you mess up enough, you could end up with an infinite loop), but it can definitely help with your post-game stuff.