Thanks! How many enemies did you try fighting? Do try it again when the shuriken and backstab ninjas are in, but right now if you're winning with just mashing, that's actually a good sign that you're good. As for the key bind, its on the to do's.
i know nothing of macs and linux sadly but the issue seems apparent: https://github.com/godotengine/godot/issues/44226
I only get to export the game knowing its a 1:1 conversion with other OSes but I guess I'm very wrong, so yeah this is a Godot thing that I can't do anything about :(