@Su.Ki
It's of course ok to point out when a word belongs to a certain variant. But not only did you add "(??)" after "English" in your quote but you had another "English?" added after the quote which you have deleted now. So, to me, it really looked like you're questioning that the word is actually English or that American English is English. Anyway, I guess from now on it's best if I always specifically state where I heard or read a word.
The term "neener-neener" is used several times in the American TV series by the character Sheldon Cooper and once by Stephen Hawking:
"Sheldon: Actually, he might have to. There’s an economic concept known as a positional good in which an object is only valued by the possessor because it’s not possessed by others. The term was coined in 1976 by economist Fred Hirsch to replace the more colloquial, but less precise neener-neener."
Howard: That’s not true. My happiness is not dependent on my best friend being miserable and alone.
Raj: Thank you.
Howard: Although, I’d be lying if I said it wasn’t a little bit of a perk.
Leonard: Who’s miserable and alone?
Raj: Me.
Leonard: Oh. I used to be like that. Then I got a girlfriend.
A native English speaker from the UK wrote on FB that he also never heard of "neener-neener" but that in his region "nèh-nah na náh-nah" or "nèr-ner ne nér-ner" are used whereas a user from the US said "neener-neener" is common in Maine.