This is exactly the same with Italian food: even though the US is full of people of Italian descent, that doesn't change the fact that the Olive Garden menu baffles Italians. Italian-American is a different kitchen. Just like British-Indian food. Or Tex-Mex. Sometimes these adaptations are pretty good (the British Indian food, which is what everyone outside india thinks of as "Indian food" is pretty good!) but for so…
I'm not really familiar with US-Chinese but you're wrong about Tex-Mex and at least one kind of Italian-American food. I'd be surprised if you were wrong about US-Chinese food because UK, DE and IE Chinese food are all awful.
In English an ethnie's way of cooking is a cuisine not a kitchen.