Hi. I wrote a json converter to obj. https://github.com/Luvideria/mcfgJSONtoOBJ
It's not super great, but It's at least more convenient for blender use.
It's pretty easy to customize as well.
I downloaded a new example and it looks like it works, see the README on github, I put an image. There is no city walls or water body yet (because I didn't need it) but if anyone is interested in it, I can implement it. I think being able to re-color every building is pretty neat too.
If you send me a file with all the new features I can also implement/update it.
Keep up the good work :)