New Orleans.

Nor-luns (locals)

Nyoo Or-lee-uns (british)

Noo Or-leh-onz (confused french people)

Its confusing.

French people say La Nouvelle Orleans as it is supposed to be ;)

I think they'd also say laissez rouler les bon temps (let roll the good times) as proper French grammar.

What would a native French speaker make of DuPage county?

https://en.m.wikipedia.org/wiki/DuPage_County,_Illinois

The name of the whole of Illinois is an American-English mispronunciation of a French mispronunciation of a Native American word which is/was something like irenwe·wa.

Versaylz, Indiana.