If memory served, they'd been over that one before since in B!Micaiah's case, Yune doesn't do anything. No lines, no attacks, just a decoration that pops up during choice animations. It's a similar reason Rinea isn't on here, since she too is just an attack decoration.
Robin/Grima is a different case I'd say if only cause of the way IS classifies them. IS doesn't classify either as "Grima" rather as "Robin: Fell Reincarnation" and "Robin: Fell Vessel". Since IS calls them Robin, I think it makes more sense to refer to them as Robin's, especially since IS lists Grima separately on CYL.