Really need to have a look back over the act one stuff personally as Celena came in at the end of act 2 but she would have been keeping an eye on the state of the world and likely the grail war so it's likely that she noticed.

In which case she may have sought her out in the time after the founding of the Arcaniss Institute, although if she seemed that she would rather be left be, Celena would respect that and keep her distance. How's that sound?