So those 90% 9 atk scrolls

Oh, that does explain a lot.

So, what's the fastest character to 30? I only have 6 accounts properly ready

Depends on what class you want to get scrolls for. The 90% scrolls were character-specific, meaning that if I wanted to get 1H-weapon attack scrolls for my Xenon, I'd have to make Demon Slayers/Avengers/Xenons/Other classes that used 1H-attack weapons.
I believe for Adventurers and characters that used either 1H or 2H (Adventurer Warriors/Mages, etc) you were given an option to choose a scroll. (Not too sure, I don't play KMS.)