I thought Bronya would be more of a sylph because she’s pretty meddlesome with the system, even though she claims her nursery isn’t illegal technically. Aren’t sylphs known to be meddlesome?

Could be, but I am wary of counting her as any of the Creation Classes, because I’ve seen her having traits of other Classes as well, and Troll Society seems conditioned towards forcing the Trolls into specific roles, so it could easily just be Jades are supposed to act like Sylphs and that muddles her true Class, rather than her being actually a Sylph.