This question already has an answer here:
Is there a word that describes or denotes a type of conversation in which two speakers speak two different languages.
In our country, Pakistan, there are approximately 75 languages, from which Urdu, Punjabi and Sindhi are common, excluding English.
So today I found two women speaking two different languages. For example:
Speaker 1 has Urdu as their mother tongue.
Speaker 2 has Sindhi as their mother tongue.
Speaker 1 and 2 spoke their own mother tongue, which are different (Urdu and Sindhi) but both can understand each other's language.
I thought that this is known as "intermingling conversation," or a "code switching." In my opinion, we can't use such words because code-switching refers "shifting completely to the other language for a word, a phrase or sentence, and then revert back to the base language."
They were in a bus and had [adjective] conversation.
They were in a bus and had [noun or noun-phrase for such conversation].
I agree that the question (which is suspected as a duplicate one to this question) is really a duplicate, but its single answer still doesn't satisfy all. In that question, the phrase "bilingual dialogue" was suggested, which I (and others may) think that this refers to the code switching as well, which I don't want here. Some words confuse the readers which sense do they mean.
I would also love to quote the comment of @Lambie regarding the term "bilingual" over here:
"Bilingual refers to one person. Not two people each of whom has a passive knowledge of the other's language but do not speak it well enough to use it actively."