Singing is a great way to learn a language - it imprints language patterns on your mind. But singing a song "phonetically" without knowing the language, can be deadly.
I sometimes have friends who want me to teach them how to pronounce the words to a Latin or German song. Usually, they want me to type up a phonetic interpretation. They don't want to learn the rules of pronunciation that I learned the first day I studied those languages. I'm reluctant - I hate things that are written out "phonetically."
I was hiking with some Swiss people in Zermatt last year. When they found out I could sing, they wanted me to sing something. So, I sang a couple of songs in German, hoping they would sing with me. That didn't connect at all. They said, "Those are German songs - we only know Swiss songs."
-Joe-