Well, I'm a cartographer-conlanger and I love putting special scripts on maps, but I agree wih Kellerica here. If you want people to understand your map, using your conlang isn't going to work.

For example, right now I'm working on a map that is going to be displayed on a boardgame shop, and it will have a fictional script that is intended to be deciphered by the passersby, so it's okay.