I know it has been more than 2 years since the last post on this thread but I had to post here. So, without further ado, spoilers abound below.
** spoiler omitted **...
I'm not familiar with either the default Pathfinder Campaign setting or this adventure path so most of what you typed for the adventure plot makes very little sense to me but I am familiar with the Realms as I've been a fan for a while now.
Looking at the wiki entry for Calistria, I can't help but think that it might be easier for you to just use Sharess (they even share at least three domains: Chaos, Charm, and Trickery). Normally speaking, most people would probably wonder what Sharess has to do with the elven pantheon but she has a tangential link in that a goddess that merged with her had previous ties with gods that in turn merged with the Seldarine.
Most of the pantheon worshiped by the Yuir pantheon merged with the Seldarine save for one member who merged with Sharess: Zandilar the Dancer. As a bonus, the gods of the Yuir have some history with the drow as well. I can't remember the details as it's been a while since I've read through my old AD&D 2nd edition material but it's mentioned in some of the books. In any event, it's just a suggestion from a Realms fan. Good luck with your adventure and I hope you and your group have fun.