I think that's different because it's a name.

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.