I dont mind singing music in a language I dont know,and I love listening to music in languages I dont know. Music is sound, after all. The literal meanings of the lyrics is only part of what the song can do for you. What does "folderiddleido" mean, when all's said and done?
   I would feel stupid trying to sing in broad Scots though, though you can get sucked into it if you're singing along with someone! With some dialect songs, the dialect is integral, as the song is used to reinforce a regional identity...in which case it's not for you anyway, though you can enjoy listening. Sing it how you feel, anyway, that's my motto.