XScreenSaver (as of 5.42) tries really hard to do something sensible with whatever set of garbage fonts you happen to have installed, so it would be helpful if you send me the output of xlsfonts on your system where it's doing something terrible.
Is there anything about fonts in the log output of xscreensaver -verbose -log log.txt ? If you're feeling adventurous, rebuilding with DEBUG defined in utils/font-retry.c and sending me the output of a run with that version might be helpful. Though I guess that if the self-compiled version does not exhibit the problem, that won't help.
