That said, there’s one caveat. Make sure it fits in with the rest of your story. If it takes the reader out of the story because it’s so different from everything else that it screams ‘I’m not like anything else in this story’ then don’t do it.
Soooooo —- just make sure the reader won’t know that it’s made up.
It’s done all the time.
I can’t count the number of times I’ve gone to a map to see if a place in a story I’m reading is real or not. Because I can’t tell by reading. And I don’t care which it is, really, I’m just curious.