You're probably right.

Republic City, Air Nomad...those names don't ring a bell.

[ And she's studied pretty much all of the world's story, so she would know. ]

I'm sure that if I would get the same answer if I were to ask about the Nora, the Tenketh, the Carja...they probably didn't exist in this world either.

Things look similar enough, yes, but that's about it.