You can greatly increase the height of your wall jump by crouching. I assume this is a bug and not a feature?

I haven't looked into the code, but I wouldn't be surprised if MC uses its movement speed modifier for jumps too, and increases its jump modifier to account for the reduced movement speed multiplier when sneaking, but this could be way off the mark. I haven't checked, just a possibility.

It's 'cause the code uses the values player.moveForward and player.moveStrafing to determine which way to throw the player upon wall jumping. Usually they're either 0.98F or -0.98F but their magnitude changes while sneaking. Fixed in the next update!