Make it when you hold the slide in the air you should automatically slide when you reach the ground the code could just be
if is_on_floor() and Input.is_action_pressed("Slide"):
slide()
idk what engine you use
next the ledge climb (the one that doesn't give you speed) i think it should always boost you in the air a little bit
Also maybe Increase the area for ledge grab so you dont need to be as precise or allow you to hold it or
Last thing personally i dont like when the spikes are like placed in a row because of the slightly long deceleration rate it was just hard to make the precise jumps
For reference i still found your game extremely fun and i think you have something special cooking so keep at it