I faintly recall using the XML checker before I was submitting the first
pull-request for those AppStream files. But then some other pull-requests
came, or maybe I just screw up the check, so the </p> element was missing.
Anyway, upstream just merged my pull-request:
https://github.com/ArtifexSoftware/urw-base35-fonts/pull/20
I will release a new version of urw-base35-fonts today... ;)