I have created the wiki page as requested (finally)
https://fedoraproject.org/wiki/URW_base35_fonts, but I didn't go through the pain of filling out the tables there completely. It actually does not makes sense for a package that has multiple fonts families. Probably the whole table would be checked, without any real value/information for the users.
So where did we end up on that use AppStream for fonts previews in Gnome Software? The urw-base35-fonts have manually written AppStream files for them, so you should (hopefully) see those fonts being available on F27+. And I think these AppStream files could be used a startup point for anyone who would like to write a guideline how to create these AppStream files for fonts from scratch. (I'm too busy to do it right now.)