Accession allows spells which Scholar learns naturally from main or sub to be AOE with a few exceptions(haste/reraise). While it wouldn't make too much sense to allow spells which Scholar can never use naturally to work under Accession, the same logic could be applied to Divine Seal/Elemental Seal(where spells BLM and WHM cannot use will receive a bonus still).

Still though, I think the following spells should work with Accession:
Temper
En-spell II
Gain-Stats

Haste is a bit too much to ask for since RDM's angle is "single target but long duration". Being able to put a 7min haste II on 12 people in 10 seconds is pretty strong and should be something only SMN can do. Gain/enspells/temper are a different story though, especially Gain-stat spells. Why would a RDM ever need to use Gain-AGI on themselves? At least make it single target instead of self target. Most Gain-Stat spells are worthless for RDM because we cannot apply it to other party members and RDM 100% of the time never needs + CHR/VIT/AGI from gain spells.