I would think, if Faith had gone through the Cruciamentum and survived, surely she'd tell Buffy about it. Since Buffy clearly has no idea in "Helpless," I think it's safe to say that didn't happen.
I also don't think it's very likely that any Slayers are called after age 18. If a Slayer can be called at 19, then the Cruciamentum doesn't do the Council much good. They've been around long enough to have a pretty good idea of the over/under for Age Called, so if they put the test at 18, I'd say pretty much all Slayers are called before then.
no subject
I also don't think it's very likely that any Slayers are called after age 18. If a Slayer can be called at 19, then the Cruciamentum doesn't do the Council much good. They've been around long enough to have a pretty good idea of the over/under for Age Called, so if they put the test at 18, I'd say pretty much all Slayers are called before then.