I am now in touch directly with some of the CPDL administrators about possible solutions.
If you are reading this message, and you have contact information for Nancho Álvarez, please forward my message to him and ask him to contact me. I would like to ask Álvarez how he makes https://victoria.uma.es/ work so well (i.e., LilyPond files display correctly within browsers). But the email address on his website did not work for me.
