I'm working on a couple of quadrilingual songs from Sarajevo, from the Sephardic tradition. One is in Ladino (Judeo-Spanish), Hebrew, Turkish and Greek (four lines to a verse, each line in a different language); the other song is Ladino, Hebrew, Turkish and Serbo-Croat... No wonder they're scarcely sung anymore!

Many years ago, I also came across a song in Hebrew and Italian, but neglected to copy it down (thinking the book would always be available to me again -- big mistake!). I'm still looking for it.

In the medieval repertoire, there are some other macaronic songs: of course, there's the chorus ('Deo Gratias!') in the famous Agincourt Song, but also Nova Nova (a Scots song in Lallands and Latin, if I'm remembering correctly) and then the lovely There Is No Ros of Sych Vertu -- Middle English and Latin.

There are also occasional French shanty songs with English lines in them, or lines in Breton.