Nominally the release is 2.13.0, but CentOS/RHEL backport some security and bug fixes back into the RH maintained 2.13.0. I see patches dating into 2019, but nothing beyond that; in a quick scan the patches all seem to be to PS code. I think the 4.3 is an internal release ID for the various patch releases.
This is a production system I am debugging on, so I must be careful to do the gs testing in parallel with the released rpm, pointing to my compiled (but uninstalled) gs when I want to test it.
Looking at this again tonight, as I understand it now, I think the only way to understand what is happening would be to download and compile the fontconfig src rpm, then hack the gs make scripts to link to the src fontconfig’s libraries. That way I could insert debug statements into the FC code as needed to check how far it gets and dump appropriate data. I may tinker with it, but I am doing this on my own time and that is starting to go beyond what I can put into the project.
Any other ideas about how to see what is happening? It is taking me a while to sort through the various structures to understand the data types and how the overall structure fits together. Is there documentation on that?
Thanks again for the responses.