People do that all the time. My favourite example is Lake Windermere. Where Windermere is lake in 2 other languages. And half the rivers in the UK seem to be named river in another language.
https://en.m.wikipedia.org/wiki/List_of_river_name_etymologi...
Here, you have two different names that you're trying to use to order a food that doesn't exist, so it's a bit different than something with a shared etymology and history. It would be like walking into a pub (again) and asking for "tako and chips," where "tako" is Japanese for "octopus." There's no guarantee that the dish exists or that the person you're talking to even knows what "tako" is.
Mandarin and Cantonese are essentially completely different languages, so you're just mixing phrases that the other person probably doesn't know.
So maybe I could try ordering a char sui tsa sui, then I can regale my grandkids with stories about how I invented the world famous dish :)
I suppose food is literally a melting pot, of cuisines and culture.
Ps, I think octopus would go better with French fries.