I wouldn't worry about it, since once you're flagged for fire, they all go away again anyway. The game seems to know which ones you have and don't, so whether the seer text is there or not won't affect your getting into sol ro's chamber. Just write each one you get flagged for on a piece of paper if you're worried about forgetting.

Oh, and just in case, you did use the portal behind Arlyxir after you killed it and get the flag message, right?