Thanks! The task UI is definitely pretty confusing, but we did our best with the limitations we had and the feeling we wanted to convey.
Yep, there is an ending! The ending varies (a little) based on how you play.
Nope, looks like you ran into a bug! I thought I added protections against invalid inputs like that, but it's possible I missed some of the battles. Restarting the game and reloading your save should get the game back to normal, though you may need to redo the fight, depending on where exactly it glitched.