The following tidbit coming from the English devroom:
"What up, Volnutts?! After discussing the issue at length amongst the dev team and also consulting all you fans about it, the verdict is in--our heroine's name is. . . . ::drumroll:: . . . . . . .AERO!!!
Yup, her name is Aero! I, for one, am relieved. That gal has "Aero" written all over her, not to mention it keeps in line with the whole four-letter pattern they had going and doesn't recall images of a certain silver-haired goon from our distant past. So let us rejoice, friends, for that's one less thing to lose sleep over."
And thus ends the Sephira saga -- the name's Aero across all territories, not just Japan anymore. Still, the question remains: why did Capcom see fit to localize her name in the first place?
Source: Capcom Unity