it is actually fairly important whether or not Mathilde hears this news before the trip to uzkulak.
the best thing that can be done with Ranald's "new power" (soul stealing) is to spread rumors of such within Destro slave hubs. Especially at trade confluences that are likely to propagate and spread the rumors.
I mean. How lucky, for one of Ranald's most favored agents to be deciding to visit one of the most hostile and isolated slave trade hubs of destro with unique trade connections towards the east that do not exist for other sorts of trade hubs, right at the same moment that his profile may be expanding to the pilfering of souls. Especially the souls of those who, in life, were not able to be liberated by any physical force of arms. Especially the sorts of souls which would be enslaved eternally in death.
I'm not particularly familiar with Warhammer lore outside of this quest, so most of this post went over my head, but spreading Ranaldism among slaves in Uzkulak actually sounds like a fantastic idea. Ranald is
exactly the kind of god they need. Not only for that soul-pilfering, but also because Ranald is great for defying oppressive power structures. All of Ranald's aspects, save for perhaps the Gambler, are perfect for the situation they're in. The ability to deceive, hide from, and steal from their oppressors, who have them outmatched in raw force...
EDIT: I don't think this is the right time for that kind of project, though. That feels like something we should spend a good amount of time and effort on, and not like something we can do while we have duties to this Expedition.
EDIT2: I think it would be a good idea to take a turn focusing on our religious side after we return from this expedition, like learning more about dwarven gods, and getting in touch with Ranaldians to see how people
normally worship Ranald... and of course, learn how we actually should go about spreading Ranaldism.
Also, it occurs to me that Uzkulak isn't the only place we can pull this stuff: we could give it a shot for any society where the lower class is heavily oppressed. Heck, maybe we could even subvert
Skaven this way, seeing as they engage in lots of slavery and oppression... and it seems like their evils are primarily caused by the horrific manipulation of their authorities, especially the Horned Rat, rather than from some inherent badness.