Sorry for the late response! Super excited for the reminder that PotF has a TVTropes page!
"Mia's Guiding Light doesn't seem to be working in combination with the removal of Panic at end of turn, at least in the final battle?"
In general, new emotional afflictions shouldn't overwrite existing ones, and Joy is no exception. So her not getting Joy in that situation is correct if she still has Panic.
"Unwilling Hero doesn't remove Panic."
It's not supposed to. Where do you see that it removed Panic state? All the skill description states is that the party will be healed. That just refers to the party's HP.
"Are Daigo's Elemental Swords supposed to stop casting elemental magic after a while?"
No, but if they don't have the SP to cast a skill, they'll default to basic attacks like every other enemy in the game. That may have been what happened in your case.
"Nice use of En-words for the elemental Fangs!"
That, uh, wasn't intentional lol. I was just looking for appropriate words to describe the states, but them having similar sounding verbs is a complete coincidence.
Thanks for the typo reports! I'll take a look at those.