It’s always funny to me when Americans try to figure out someone’s location through variations of the English language. “This person says uni and diner, that’s not consistent, that must be an American trying to pretend they’re British.”
Have you considered that people who aren’t native English speakers have been exposed to different variants of the language and choose to use whatever words feel more natural to them?
I don’t give a fuck if I’m “consistent” or not in informal situations.