There is an option in game difficulty to have stat drain effects removed on rest. I've turned it on after my character wasted the scrolls by fumbling the umd roll. The priest in the tavern you buy them from says he will cast them for you, but it was still my character who cast it. I am not sure if it was a bug or if this is how it's supposed to work.
In Kingmaker it picked the highest caster level person in the room for it. It didn't matter in the end because scrolls have a fixed caster level for everyone except a Scroll Savant subclass, so dispelling some curses with DC of something like 42 was impossible even with proper spells, let alone scrolls.
Why they didn't implement a temple menu akin to BG1/2 in their second game after the first one already had a system that was downright abysmal, I have no idea.
