Hi @Crel,
At the moment, spells are hard-coded into the app, but I will start working on a way to allow user-created spells. It was always on the roadmap, but there were a bunch of bigger pieces that needed looking at until now.
You can associate cults once they are created in the system, which creates a bit of back and forth (I.e., you need to go and create Subere cult and then go back to Kyger Litor and add the association), but was the best way to allow for users to take the system in their own directions.
Feel free to add any issues or wants on the Trello: https://trello.com/b/cDEVQreh/runequest-app