On the other hand...

My sister, who's a better researcher than I (a librarian, so she has better resources, and retired, so she has more time), found a children's play/ebook by that name dated 2002 and written by Louis Lippa (not Pippa).

It has snippets of songs in it -- not The Troubadour Song (at least in the part that's available as a sample), but many others. It does make me question the information I found.

That would explain why I haven't found any reference to "Louis Pippa" anywhere other than the two sites referenced above, though I wonder where the 1928 came from, in that case...