I think the Kunai stiff ninjutsu thing is a bug rn. I agree with the discord thing. Imo it's better to practice movement combos if anything, just to familiarize with the cd's and then you can start to customize and freestyle.
Grinding helps with all of that. Move from pack to pack, memorizing cooldowns, etc. I dont think it is a bug otherwise you could throw kunai stiff over and over again. And you dont want to consume the ghost rune when you have 3 otherwise you wont get 3 rune wheel