There is a kinder variant for such - prosecco, which can actually mean OK quality (within sparkling stuff bounds, which are not high).
replyBut yeah calling anything Champagne apart from stuff coming from Champagne is a bad form and looked down upon a bit. Small kids do such mistakes and thats fine, adults shouldn't.
Not all adults care about the origin location nor should they.
replyIf you’re ordering “sparkling wine”, you are not going to get a wine made using the méthode traditionnelle.
replyYou will get an entirely different style of wine.
The origin location is really secondary. “Franciacorta” gets you something like Champagne, “sparkling wine” does not.