Thanks for all your work. I have become at least partially convinced that the problem that must be addressed first is why I am getting the error when I add the fonts. I go through the process - right-click, add existing items, add the font and Validate. Get the error:
This resource is present in the OPF <manifest>, but it's not reachable (it's unused).
And until I get this worked out nothing else much matters. This error message is coming from adding the fonts, not from the stylesheet and, since the fonts are ignored, perhaps the stylesheet entries are being ignored as they refer to the fonts.
Just to let you know - there is no folder path displayed in my version of Sigil that I can find, but I know how software works (in general) and found the path in my /users folder. The fonts are indeed getting added and the paths are indeed ../Fonts/... And, just to let you know, when I finally realized that all of this referred to the Sigil work folders rather than the source folder of the fonts itself I felt like slapping my head and saying something smart like "Duh!!".
I will start checking with the Sigil forums to see if I can get this resolved, but I wanted to thank you again for all of the time you have spent on this for me. I believe that there is something specific going on in my system that I need to get resolved before any other problems can be addressed.