If I recall, status proc quartz do apply to crafts, but I have no idea what the formulae are or how they work. A 10% Freeze proc chance should still be a 10% chance with a craft, resistances notwithstanding of course, though if the craft has its own inbuilt freeze chance I don't know exactly how they interact. I would expect either two proc rolls or something else resulting in a generally higher chance to apply than if you weren't using the quartz. That's what common sense tells me.

Myself, I like to load my pure-fighter types with lots of stat-boosting, effect-applying quartz so they'll hit slightly harder and have a chance to disable the target and I don't worry too much over exactly which status effect is being applied. Obviously some are just better than others but if the enemy can't fight back on its turn that's good enough for me. A strong offense is the best defense and not letting your enemies get turns is always the strategically correct decision.