Editing this file will require a server restart or you can use /wizards finish <Map>, this will recreate the game; loading the new values from the file.
Additionally, the file can have extra data like the arena display name; you can set a display name by using /wizards setDisplayName <arena> <display-name>. This will make so the arena name displayed on chat and by the scoreboard will be custom, but the file names will be the same as before.
You can also manually add a blacklist for the Min-Y-Explosion setting, any blocks on that list will explode regardless of its coordinates.
That's it for map config, everything else in this file is reserved to store location data, you don't have to touch this; everything is added via command, but you can remove a location if you want to. Example: