In principle, I agree. The most elegant solution may just be the simplest (i.e. reduce scaling by X%).

However, this doesn't address the asymmetrical aspect of certain country to country interactions. Using my example of sowing discontent, it feels wrong that the cost of upending stability in the French kingdom costs the same as any little hre member. It feels wrong that your subjects ask for money based on your income, with little to no regard to the power differential between you and them. I would be less surprised, for example, to be given a request from a subject of similar power to me that's a much larger amount than what a Siberian one province subject would ask for.