You're talking about letting the player jump a few frames after leaving an edge right? That was definitely on my list of things to add... I've never played Celeste, but I wanted to implement a lot from this thread: https://twitter.com/MattThorson/status/1238338574220546049. I did get the wall jump buffer in! You can perform a wall jump from about 4px away from the actual wall, it made a huge difference.