Can't watch the video right now, but could it be that one of the symbols is a slot for the summons? I honestly can't remember if there's a specific menu for Astrals.
And I think that it's fair to assume that, if any other AAA is gonna use Luminous after XV, it'd be Tabata's new game?
I hope it's a new AAA Jrpg series. I'm tired of automatically only thinking about FF, KH and DQ as the only big ones S-E has to offer from that side.