Each type of event has a different name within the game. If you look at the base game freeplay map in the editor, you'll see certain names placed on objects. That'd be how you name the objects so the game knows it's an event.    you can't add in new events to the game unless you run a mission script. What you can do is make an edit to an event type that already exists. Like instead of listing an MVA as that in the callout, you could call it a physical rescue, and then you could include