I think you hit the nail on the head there.
If I was DMing this adventure I would actually do it as I mentioned. Allow her powers to stand until the crisis was ended, faith or not. Then would require the player to make a direct choice and would use a specific quest line to fully bring her into Selune's favor.
This makes perfect sense. Rebuilding her faith should take time, it would be jarring if she turned into a zealous Selûnite before the end of the game. So I believe that she takes the power out of pragmatism initially. Not really knowing where that path will lead.
![[Linked Image from i.imgur.com]](https://i.imgur.com/iecPtBi.png)
I do agree that the game leaves it up in the air. But that is a matter that should be settled in the epilogue. Selûne powering her up until the end of the game makes sense to me for the reasons I stated before.
Her epilogue needs to show how she will cope with her trauma and grief/shar curse. Perhaps she will find solace in a Selûnite cloister. Or maybe she decides that she has had enough of gods and finds something else. I could even see an unromanced (white)Shadowheart with dead parents turn back to Shar to forget. That version of her is so devastated and alone.
So in a nutshell: I think her Selûnite path is well done and makes sense. It just lacks closure, like many other things in this game.