Alright, even to this day people still debate about who won soul storm.
Now since we really dont know "only know the Blood Ravens Lost" I have made up a possible scenario of what happened. And if it turns out cool, I will go ahead and try to make it a MOD.
So basically in this scenario you should have the choice to ally up with one fanction in the game. In this case the Imperial Guard ally up with the sororitas after they make a pact and Stubbs show's his strenght in battle.
By the time Stubbs and his guard went to the Blood Ravens stronghold - which happens near the end of the campaign - iit was already too late. The Blood Ravens had already been beaten by the Tau and the planet was completely under their grasp as well.
Vance Stubbs led an invasion on the planet and where succesful in their conquest, there they allowed the remaining surviving Blood Ravens - more or less a company and a half - to gather back what they could, armament, treasures and their precious gene-seed alongside their death.
Once the campaign concluded, the Imperial Guard ending goes on but one planet also becomes a convent base for the Order of the sacred Rose. And thus Kaurava becomes a shining for the future of mankind where bold warriors loyal and faithful to the imperium of mankind are born and trained daily.