Questions!!
I do not believe that Elora has cast any spells up until this point in the game, though that three month time we lost is a little fuzzy. I don't think she's "revealed" yet that she's a source. Obviously she's just cast in front of Tal and she'll deal with that in a few moments however that works out. She *did* set off the blood moon -whoopsie- but I don't think there were any spells. Unless someone recalls something?
Obviously someone could have had their own way of knowing and figuring it out and she hasn't like, hid it magically or anything like that. She just hasn't announced it. Maybe it's just obvious by her natural pink glow. I don't know. lol
Are there clerics in Witcher? Like, people who can cure without being Sources? Or, if you are healing someone with magic, you are a source of magic and that is that. You know what I mean?