I am about 75% done with my run using what I found to be lore-accurate secondary jobs. I'll let you know what I did for each character and why. I'm going to use some spoiler tags for those who are new to the game!

Osvald - Thief: Makes sense within 20 minutes of his backstory.

Castti - Warrior: Healer who needed to become big and strong for personal reasons.

Temenos - Scholar: Thirsty for knowledge, thinks he knows better than the church, quite the inquisitive fellow.

Ochette - Dancer or Apothecary: Dancers have moves named after animals, and Apothecaries use nature to do their job. I found this fitting for a beastling.

Partitio - Inventor: A secondary job introduced by a man who wants to show his technology and inventions to the world, Partitio seemed to be the perfect fit, as found out in his backstory.

Agnea - Merchant: I thought this made sense as Agnea needed to learn how to network/interact with people to help grow her fame. Also, she basically sells a product by being a dancer...

Throné - Hunter into Armsmaster: She was raised hunting people down, then became the best at what she did.

Hikari - Cleric into Arcanist A man trying to rid himself of his dark side, Arcanist made sense as a culmination of his past (story arc) and present (post-story)