Try this.
https://www.mediafire.com/file/7xo89...range.xml/file
It didn't immediately crash the game when I tried starting a world with it, so you should be able to get that far at least. :-)
I'm still working on the piece that will turn regions into Nations, so I moved Quintana Roo by hand and and just adjusted Mexico's population manually. Also the new Nation is called Yucatan, but it's a simple thing to rename it.
Miskito Nation defeated me, however, as I don't think that autonomous region is in the default world file.
As I mentioned, the program just copies over the ethnic distribution of the old parent nation, so you'll probably want to adjust thoseĀ-especially for QC, NU, and Yucatan. Along with stuff like denonyms etc.
Let me know if it works (or totally messes stuff up). I play with the world file creator more than I play the game at the moment.