Agreed. IFK for non-physical offences/DFK for physical offences on the touchline nearest the incident seems like it would be a sensible "catch-all" situation for anything that occurs off the pitch. Trying to work out what the role is of the person who has committed the offence, what the role is of the person who they have committed it against and if anyone stepped onto the FOP at any point all seems to be adding unnecessary complexity.
Doing that under pressure in a match situation where the players want an answer now is also going to complicate things.
I think this is one I'm going to have to revise on every week until I can get it into my head.