Hand of the Apprentice grants critical specialization on a crit. Some critical specializations force a save against the wizard's class DC, 10 + Intelligence + any proficiency the wizard has. Is the wizard trained in this DC? Seems like those crit specializations quickly become useless if not.
1. Yes, all of the casters are Untrained in Class DC.
2. Using Spell DC in place of Class DC for edge cases has been common, and usually good, advice for how to run the game for a long time, but is still a houserule.
3.From the Animist Playtest, it looks like in the Remaster, casters are at least being Trained in Class DC to avoid those awkward cases. (As speculation from a playtest class, this could still be wrong).
That's a relief if all casters are about to the trained in their class DC. I'm playing a warhammer tosser in PFS, and allowing the enemy a DC 14 Fort save at later levels would just be bleh. Currently, there's no save, but I'm told they're adding one in the remaster.
3.From the Animist Playtest, it looks like in the Remaster, casters are at least being Trained in Class DC to avoid those awkward cases. (As speculation from a playtest class, this could still be wrong).
I'm fairly sure I saw it confirmed that all spellcasting classes are getting at least trained in Class DC as part of the Remaster.
I can only speculate about any of them getting better than Trained proficiency though.