It is working, i know because i have done that hundreds of times
Those visible places are where settlers/warriors use to be, easy to fix in world builder. Player infos are the key, map infos only points the places where settlers are but player infos determines civilizations. After you get the right civs and no defeat bug its only worldbuilder work and saving those changes, right?
And by the way, I have make at least one pretty good world map with 28 preset civs for and 1.75. Its 100x50 standard map but it feels almost like huge

100x50 map is the biggest that my ancient 3ghz single core can handle

huge maps game slows badly after 500 turns but my own map i can play all the way to trans human era

if someone want and can tell me how, i can upload that map