That is such a cool idea for a puzzle game !
Know when working with Godot : The Input system actually adapt to the computer the player is using, i actually have a AZERTY keyboard, so the A and Q are switch for me.
So when searching you tell Godot to listen to raw inputs : so the A is still a A,
but to quit you have set it to Q physical : so also A for me.
Not a big deal but still interesting to know :)
Loved your game !