And by the way, there is nothing at all in any of the things I've seen in the Mudcat, describing what it is for, that indicates that it is for "English language" folk songs.

My understanding of what the Mudcat is for, based on what I have seen indicated in the description of the site, is that it is for "folk music and blues".

Folk music encompases all languages and cultures, and it includes instrumental music as well as songs.