I received the following email from MuseScore:
"Your score has been taken down
We received a report that your score "Ecce quomodo moritur justus" is infringing on someone else's author rights. We have taken down this content from MuseScore for the time being.
Reportedly infringed copyright:
Song: Ecce quomodo moritur justus
Publisher: CEDRO (Centro Español de Derechos Reprográficos)
You can dispute this report, if you believe the copyright content has been mistakenly identified or if you have obtained all the necessary rights, licenses and/or permissions to upload and share this work on MuseScore.
In order to do that, please go to the link:
In response, I filed a dispute thread as proposed, arguing that this work written in the sixteenth century has long been in the public domain (CPDL), as can be seen here:
Besides, on the PDF downloaded from this site and from which I edited with Musescore, the following statement can be read in full:
"Copyright © 1999 by the Choral Public Domain Library (http://www.cpdl.org)
Edition may be freely distributed, duplicated, performed, or recorded."
I don't have an answer yet, but I would like to understand how I could usurp anyone's rights.