As one of those who is costing the party a large share of its treasure, Tsadok will do whatever the party likes.
He does ask, if we purchase the scroll, does it have a limited? In other words: Can we continue to decline to see if we might get better? If not and we use the scroll, will it fully heal us?
The scroll has four copies of the spell Restoration. Each use will completely heal the ability drain for one ability score (there are other uses as well; although none pertain to the party you might want to read the description of the spell in the Core Rules).
Your only other options are to wait and hope you find potions or scrolls of Restoration in your adventures or to wait 'till Aodhan can cast 4th level spells.