Anyway I took the time to investigate
https://forum.xpdfreader.com/viewtopic.php?t=36
xpdf is definitely *not* using fontconfig, it relies on hardcoded font
locations, you probably just need to adapt them to the new urw
locations.
And then you will hit PS1 vs OpenType if this part of xpdf is not ready
for 2000 either.
--
Nicolas Mailhot