You worry overly about nothing.
An example:
"#@%&!!" Chad screamed out.
Though the dialogue isn't a word, it is known by association, that it is a curse. What curse, I have no idea, I can just insert whatever I want.
An example:
Your foreign character is on the phone speaking german, when another character walks in. You can type the dialogue in german, using the characters' actions to let the reader fill in any blanks needed.
Maybe the german upon seeing the other character, cuts his conversation quick, and hangs up quickly, switching to english. His actions would give indications, not of what they were saying, but that he considered it private for some reason.
I guess what I'm fishing around, is that one sentence, phrase, cliche, does not rely on itself to tell its story. Words aren't independent in a story, they are a family.
So in summary, I believe as long as it is part of the story, and not just a part in itself, you shouldn't have to worry.
Best writing to you.
Oh, the above text is only my opinion, not some rule.