If you are in the same region as the diplomat, and possibly adjacent regions, you should get a report that someone has influenced the locals. Not sure about the adjacent regions, though.
Are you certain that works? I have never seen it, and I asked around when I used the option and no one ever told me having seen it. I have used it in regions where people *should* have noticed....
If actions were public, this would remove a big difference between priests and ambassadors.
