alt Hacker News>"I was in 東京 yesterday"
I think it's the wrong example, because this is actually very common if you're a Chinese speaker.
Actually, people tend to say the name of the cities in their own countries in their native language.
> I went to Nantes [0], to eat some kouign-amann [1].
As a French, both [0] and [1] will be spoken the French way on the fly in the sentence, while the other words are in English. Switching happens without any pause whatsoever (because there is really only one single way to pronounce those names in my mind, no thinking required).
Note that with Speech Recognition, it is fairly common to have models understanding language switches within a sentence like with Parakeet.
Okay, it's getting clear that I'm in the wrong here with my insistence that languages don't mix and foreign words can't be inserted mid-sentence, yet that is my experience as well as behaviors of people sharing the language, incidentally including GP who suggested that I can always do the switching dance - people can if wanted, but normally don't. It's considered a show-off if the inserted word could be understood at all.
Perhaps I have to admit that my particular primary language is officially a human equivalent of an esoteric language; the myth that it's a complex language is increasingly becoming obsolete(for good!), but maybe it still qualify as being esoteric one that are not insignificantly more incompatible with others.