I like Janna, I do, she's funny at least, but I think she's more of a collection of quirky tropes than an actual personality, at least right now.
The only two times I can think of her actually having a personality are in Bon Bon when she's upset how Star cares more about Marco than hanging out with her, and in Sleepover when she's self-concious about liking the colour pink.
I think this is something the writers could do some really interesting stuff with if they're self-aware enough. The way I see it, Janna is really self-conscious and has identity issues, and self-casts herself as this quirky person for attention. Maybe they'll make a point of this for her realising that she doesn't need to do that to have meaningful connections with her friends.
Think of it like that episode of the Simpsons where Bart gets into playing the part of the class clown, but then becomes deeply uncomfortable when he realises that's all other people see him as and he feels more like an actor than an actual person. It doesn't mean that Janna isn't into the occult and all that weird stuff, but I think she definitely hides herself behind that because she doesn't think she's interesting enough otherwise.