The above problem isn't exactly true for male Viera, obviously, who do get three flavors of forenames in their generator pool: female Viera birth names, masculine city names taken from other races, and masculine-sounding icelandic names. ...The last example in that list is tricky, though, since a lot of those names aren't 'real-life' names. This happens in the female Viera pool too, but the ratio is different.
I'd be completely inclined to believe they don't have a concept of masculine names in their native tongue if it weren't for that last variant, anyway. Particularly since the two seemingly city-born male Viera npcs with names use conventions from two of the most populous races in Sharlayan: Erenville (a rava using midlander conventions) and Charmont (a veena using elezen conventions).
Then there's Loifa, a veena from the SGE quests, who actually was a wood warder and taken from Skatay Range forcibly. It sounds more 'feminine', so I guess he kept his birth name? Maybe? 'Loija' is in both the mViera and fViera generator pool, although it's a letter off...
Loifa was also under a wood warder master before he left, so maybe he had something to do with that? That or whoever names npcs really did just decide to change a letter for funsies.
And of course I still can't even begin to guess what's going on with the surnames, though I think the eorzean calendar comparison with rava surnames is really interesting.