The other Sidhe are more “monster manualish” so need to be “cleaned up”
No one ever tried to play a “Ban Sidhe” character so there’s not a lot written about their culture.
Of course, now that Teen Wolf has gone there (a while back even) and actually has a banshee, I suppose if the game were to be published, we’d have to write up a culture for them….
One big problem I have is that there is a big cross-cultural assimilation of “Earth” mythology all piling up in Astlan like a melting pot (or a refugee camp).
From the book’s perspective, there is a very good reason for this which will be come more clear in II and III. But the problem is, integrating it all and describing it all is a huge task….so some of will be on an “as needed” for the story basis.