@Wandarine - I’m glad you think it fits the overall vibe and style! That’s what I was worried about with Firefly.
@etoilelumineuse - I love that you love it! 
@venezio - That’s what I was worried about with Firefly. I just really like the flow so much better this way than the other, more practical options.
@snowmaiden - I do think it’s a more unique word name, even more so than Reverie. But I’m glad the vibe matches!
@Greyblue - I do think it’s more wordy than most of my other first name options.
I forgot to mention that this I am considering this combo for Sylvestra nn Sylvie (from this aesthetic). I’ve had a lot of trouble with this combo, namely because I can’t find anything I like with Sylvestra in the first name slot. I also really love the flow of Oona Sylvestra, and I prefer Firefly Oona Sylvestra over Oona Sylvestra Firefly, especially since our kiddo calls one of my partners her “Uma.”
This also wouldn’t be the only combo on the list where the first name wouldn’t be the use-name - Rowan Taliesin Iroh (Tal) and Soren Tiberius North (Ty) come to mind. Does knowing that she would go by Sylvie change anything?