If it is not noticed, then it should be. Spending enough time and money to influence the views of a significant enough portion of the regional population to actually make a significant difference should be noticed by other people. Not being noticed definitely sounds like a bug to me.
Noooooh! It's not a bug, it's a feature!
Seriously, I think it's great. The result is not as dramatic as what a priest can do, there is no "Diplomatic Take Over" for example, but it has the advantage of being covert.
It is realist too, talking to the right people without anyone noticing is what spies do.
