This is more like a trick question, but I think I found a bug that for some reason, it decreases the minimum distance for setting a city.
I think minimum distance is like 9, and I just realized I am creating a city right next to it! (only 5 tiles away)
First of all, the distance differs depending on the size of the map.
You can change the distance between cities in different map sizes by altering these values in ElementalDefs.xml
Yes, that's what I found, and anything else does not work.
i.e if you make a new entry like
It won't work. The game engine won't read it. Oh well, as I said, Stardock will find out this soon enough.