Is there anything official about what is going on at Raus Fort, post Argrath taking Pavis?
Nothing Official at least not yet.
However, let’s start by remembering how few people we are talking about. In the “Grantlands” (and by that we mean the Zola Fel valley between Sun County and the Rosgali Sea), had 10k people in total at its height. 4k of those are river folk associated with Corflu, plus maybe another 2k farmers at the river mouth. So let’s say there were 4k Grantland settlers in total, maybe half of them in Raus’ domains.
The nomads want the rich grasslands of the river valley. Left to the nomads alone, the likely fate is for those settlers to become the newest oasis people in Prax. But the nomads accept the leadership of a Sartarite, and Argrath (or his senior lieutenants) is certainly open to a deal where the settlements acknowledge his rule and come under the protection of the White Bull. Some raiding will of course take place, but low-level, like what happens in the Guardian Hills.