After what felt like a very long weekend of debugging jGenerator, I finally figured out what was going wrong, and how to fix it. It didn't make sense at all, which is why I didn't pursue that line of investigation earlier. The library worked fine before. It hadn't changed. Then it didn't work. I was figuring that meant something outside of the library had changed, and had borked something used by jGenerator.
Whatever the cause, I wound up using a java decompiler (jad) to figure out exactly where the problem was, while comparing to the versions of available jGenerator source code. I removed what appeared to be the offending line (calling Log.logRB() - which is a utility log method within jGenerator), and recompiled a fresh copy of jgen.jar using the Ant build script.
Deployed that sucker, restarted the Mavericks instance of the Pachyderm authoring app, and cÃ©st voila! I had it working early this morning, then published fresh copies of all of the Mavericks sections for review. *touches wood* It's working great now!
So... in the future, when debugging something that isn't behaving as expected... throw away all assumptions - no matter how "sure" you are about something, test and verify each and every line of investigation.
OK. Murphy, you can go to hell now...