So, apparently Chrome will translate Алиановна as aliased which I just discovered by googling to this page. But looking at the actual website, it looks like a table of forms of the name Aлиан— Alian / Alianovich / Alianovna, and then plurals and declensions, not alternate meanings. So I don’t think it actually does mean aliased, and that google translate is handling that strangely because English doesn’t have patronymics, or grammatical gender. (If I’m wrong about this lmk, my Russian is very basic.) Anyway, I wouldn’t be surprised if Claremont tried to give her a name that meant “unknown” or “alien” or something clever and thematic.
N.B. that if someone lacks an obvious patronymic for whatever reason— an unknown father, for example, standard practice is to invent one rather than do without. Since we really don’t know anything about Natasha’s family, except that she was separated from them at a very young age, it’s possible that Alianovna is a made-up surname. She could have plausibly been born with a different name altogether, though her connection to the Romanov dynasty is attested to by comic book mysticism.
Even if she was born Nadia Lupova, though, I’d argue that Natasha Romanov— however you want to spell it— is her real name. That is the name she knows herself by, which matters more to her story, than whether it was the name she was given.