AH!!!
I didn't realize that you have to make edits both within the Autobattle editor, AND within the Solobattle editor... but it makes sense, since the Rubicant battle is both.
In retrospect, this seems like a dumb question. Thank you for your help!
EDITED TO ADD: Making that change allows my chosen actor to show up in the Autobattle as he should. Still one problem, though. The actor is 15, Golbez. But when he shows up, all he will do is attempt to cast White Magic, and it fails. Even though I have the Autobattle script set to just cast Flame, then be done. Is there something about the Golbez actor that makes him unusable, or am I missing something?
Thanks again...