Okay, I think I've figured out my issue: I'm a chronic multi-tapper - if I don't get immediate response, I'll sit there clicking until the cows come home, which in a game about morse code is not the greatest lol. Basically, the spell feedback feels a little bit delayed, so I think I thought my keyboard wasn't working when actually, the game thinks I'm making a combo move of a bunch of little taps. I almost wonder if maybe there's a way to adjust the visual feedback or add a delay to the combos based on what spells have been unlocked - kind of teach the player to press in a rhythm instead of button mashing.
Otherwise though, I adore the concept and like the art style!