There is a map I enjoy playing but it needs some tweaks
I want to alter some bonus regions split a couple up but leave the map as is
Am I allowed to do this

And what if I wanted to add to or change artwork on the map

Idk I was wondering that too

You can change bonuses once you are level 45 tho

If you wish to make small changes to a map, it's probably best to provide those as feedback to the map maker and see if he wishes to implement those changes.

If you want to change the map yourself, try contacting the mapmaker for the original SVG file. If he doesn't want to provide the file, he probably doesnt want you to change the map either....