(Since they are related to the umbral events)
Actually, they really aren't. they're only related by circumstance. The primals existed in the game's story before the 7th umbral era events began. In fact, their battlefields existed in the game before this as well. The only connection they have to the 7th umbral era events is the beastmen that are calling them.

White Raven is related to the Umbral event just as much as the primals are. White Raven existed before the Umbral event
You don't seem to realize what happens to him after you beat him, do you? He's not coming back.