I think more than half of our cherished folk songs are "fakes" in the sense that they suggest a society context which was not the author's own, and possibly never existed in real life (- not even if we disregard the miracles). This includes old anonymous songs, but has become a real pest since the 19th century, when folk songs were discovered as useful material for nationalist and other ideologies.

Faking convincingly enough to fool a scholar is not all that easy; "genuine country folks" are not as likely to succeed as poets are (including teachers, clergy, fellow scholars).

A similar situation, set in Bavaria about 1900, but with a different ending, is described in "Das Volkslied" by Ludwig Thoma, unfortunately not easy to read, let alone translate.