She was refered to as Titania (The Fairy Queen) so she was not an alf but instead queen of all fairies exept oboron (Sugou or The Fairy King)
You all are forgetting something important the only reason she looks different is because she was freed she uses the same avatar for Titania and her normal account for ALO. So since the reincarnation update was never released she was an undine the entire time. Plus we get a hint of it when Kirito says there is an Undine and Spriggan Alliance, yet he hasn't meet any undines at that point. Unless Agil recognized her as an Undine because we've seen he has played the game before.
The Titania account probably does not exist anymore, and it had no race affiliated with it as far as we know. She has two ALO accounts, her usual Undine one and a Sylph one called Erika.
Reincarnation update? What are you talking about, Incarnation as a general concept only comes up in Alicization. There was no "Reincarnation update" for ALO.
The alliance is completely unrelated to this, he only needed to name a race that was not present at this conference so nobody would be able to verify it in a matter of minutes.
@Bianite: Be nice, there is no need to attack others. I don't want to have to tell you again.
First, as ZeHaffen said, calm down.
Second, you are totally right, the manga doesn't matter whatsoever. The Light Novel is the source material.
Third, I remembered the update, but under a different name. Reincarnation is not the best choice of words, as Incarnation is a totally different concept in the yet unanimated Alicization arc. I just checked, the fan-translation used this word too, it's been years since I read it, sorry about that.
Actually, in Mother's Rosary, she stated her Sylph account was "more for" duels/combat, because as an Undine she does healing and her Berserk Healer thing.
And in the same book, she says that the main reason why she has a second account is for variation in her appearance. Giving it a specific use doesn't mean it's the reason why she created the account in the first place.