I love WallJump and in combination with ElenaiDodge2, its very smart. I was happy to see ED2 gets updated and take the vanilla friendly way. I suggested her a skill book for cooldownreduce and weight limit highering. She like it.
Maybe you could make a skill book too. But by WJ the book could be enchantable and gets tiered.
tier 1 - normal WJ book = wall jump skill
tier 2 - diamond WJ book = wall jump and one air jump
tier 3 - emerald wj book = wall jump and two air jumps
If the book stored you gonna behold your skills, but to get the next tier you allways need it.
That would make it absolutly vanilla friendly and a book is good for creating the gui in vanilla style.