Re: Cease hostilities! What's the best way to edit the game to make this more playable?
If you get an error now then you have a made a mistake when editing your files. There could be a clue in the log.
The error message as such is generic and doesn't refer to any particular error, for that you require to be able to read the log.
I seriously suggest to use my set up to start modding: there are a number of pitfalls (like the Ragusa map error, the mongols winning) that are removed. In principle it is the grand campaign with kingdoms capabilities (hot oil, yes\no events, expanded scripting).