I've been thinking about adding a rumour mill to things, but it requires expanding the scope of the active world immensely for the information in it to be meaningful, all for the sake of a handful of lines at the end of the turn. It's a lot of work for a little flavour, where ideally I want things to be the exact opposite way around.
Well... prefacing the following with a note that I like this quest a
lot and don't mean this as some sort of condemnation of what has been, overall, some excellent writing...
The commander of Swartzhafen has been on our informant listings for years and we've never heard anything about what's happening in Swartzhafen, or indeed received any indication that his "informant" status means we're kept informed of anything at all. All those towns that we fought our way into getting people to report to us from might as well not exist for all that we learn about them; are those bureaucrats and headmen being difficult and hiding things, does Mathilde not bother to read any of that stuff they're sending in, or was getting them to become informants simply irrelevant? We paid to put agents in the military and on the Sylvanian border, but the only time we learn about those topics is when Van Hal or another councilmember tells us about them, and the agents that we've been pushing into the Watch don't seem to be telling us much about the attitude of the rank and file Watch personnel to our takeover- we only know that the leader resigned and that was done in person. Indeed, the only time those veterans appear to exist is when they're sucking down our discretionary funds. We've made use of our village connections and the thieves' guild but only when action choices involved making use of them- the only time I can think of that we actually got information out of them without it being directly related to our action choices was when it was mentioned that the thieves said Kasmir was looking for a priest of Ranald (which was great and exactly what I'd like to see more of).
So, I agree that the work:flavor ratio is important. Right now, overall the flavor I'm getting is that Mathilde is throwing tons of cash at building a network but doesn't actually use her network for anything; she has them sending in paperwork and someone reading the paperwork but there's no practical
result of all of that effort so it's just spending money on busywork. It wouldn't surprise me if one day it came out that she was getting shamelessly fleeced by a large fraction of the people who supposedly work for her since they can collect paychecks without really doing anything aside from sending the occasional "all boring here" note unless she shows up in person; there's nothing I see in the updates that contradicts this interpretation of her character and performance.
Maybe a rumor mill isn't a work-efficient way to go about changing this, but I don't think that this is the sense you're trying to convey about who Mathilde is and what she's accomplishing. Her job is to be the one who knows things and right now it still feels like she's usually the most clueless one in the room when the topic is anything she hasn't seen with her own eyes. Even dropping a handful of sentences into the updates about what she's hearing from one source or another would make a huge difference.