Thanks for the update! I improved my playerscript over the last weeks myself and what helped me for good walljumping are raycasts that detect the walls and the correct direction plus the coyote timer is working on them too, so if you'd pressed slightly to early in one direction, the jump will still be possible.
Viewing post in 2D Platformer Controls in Godot Engine comments
I am not good with raycast so I made them with timers (especially yield code) In v3, if you press jump direction when you are on wall, it doesn't move you for a little time and you can still wall jump. it gave the character (or box, I guess) a sticky feeling like super meat boy. HTML version is updated too, you can try it if you want