It's nice but my problem would be that no one would ever call her by her full name and she'd be
Sera (boring) anyway. So I wouldn't use it.
Also, someone once wrote that the seraphim (fire angels) burn and suffer for eternity and always repeat a certain phrase or something. I don't remember how that went exactly, sorry. But the associations with the seraphim isn't as nice as it first sounds.
Seraphina looks pretty but I find
Serafina more manageable. Both work well.