Quite nice the distribution you made, also I found this mod named Language Barriers
https://mods.frankkulak.com/#/ts4/languagebarriers
"GrumpyGlowfish;c-17733677" wrote:
City (West):
San Myshuno (capital), Evergreen Harbor, Newcrest, Magnolia Promenade, Willow Creek
Desert (South):
Del Sol Valley (capital), Oasis Springs, StrangerVille, Selvadorada, Sulani
Countryside (East):
Windenburg (capital), Brindleton Bay, Britechester
Highlands (North):
Mt. Komorebi (capital), Granite Falls, Glimmerbrook, Forgotten Hollow
Then even with that mod could configure each region with a language
Simlish for City
Windenburgish for Countryside
Komorebigo for Highlands
Selvadoradian for Desert