Thanks for the feedback. I'll look into adding that functionality. You could write a little program to convert the map file to json.
iirc I tried to explain how the map data works in the readme.txt. I believe the "retro map data" is a raw data dump separated by spaces so you can see it in a text editor and import it into anything you want or convert it. If i get around to it, i'll try to make a program to convert the file and upload it for you.
I haven't worked on it in a while, so i'm a bit rusty. I actually have a newer version or modification of it that i've been meaning to upload which edits chunks of a map and stores them in one file for a roguelike i'm working on. each chunk is a room like binding of isaac or a screen in the legend of zelda. If that would be of use to you, i could upload that too.
edit: Oops! I just checked and i guess I didn't specify how the save data works in the readme.txt.