I have found the orignial SIL-licensed files available on the internet, and have made a new GitHub organization and corresponding repositories for the fonts themselves. Please see
https://github.com/OpenLilyPondFonts
I'm happy to add other contributors to the repositories, and would like to add example usage .ly scripts as well but I just got this going and wanted to share with people here early.
I know that this might be somewhat controversial (as it seems the original authors are trying to hide the content) but given that this is fully intact with original SIL open font licenses, etc., I'm confident that this is the right thing to do to keep these files available in their open form.
Steve