Map errors are fixable only on the map graphic itslef.
All other can be edited in a text file (in fact we use an excel spreadsheet)
But I believe that statement about map errors only applies to the graphic of the map, not the popup text and the words that appear. Those I believe come from a reference file and are not printed on a map, because the control of towns can vary, and therefore the background colour of the label varies. Where the words 'New Hampshire' are spread across the map to tell you that the area within these borders is generally considered New Hampshire, that cannot be edited without graphically editing the map. But the popup text I believe is editable.
So if I were to edit the town names, leader names and unit names, which files would I edit?