Lake Texcoco should be renamed as Valley of Mexico, which is more accurate; naming that region as Tenochtitlan is like naming the Andes mountains as Cusco. Other recomendation for Mexico is Sierra Madre map.
In Central America, it is weird that there is no Petén Basin for Guatemala and Lake Nicaragua for Nicaragua.
In North AmericaI, I would like a Québec map and a Black Hills map.
In my opinion of main maps that you didn’t mention in South America: Llanos which is the main countryside region of Colombia and Venezuela. Also Antiplano which represents Bolivian part of Andes mountains. Misiones which represent the main region where Guaraní were evangelised by the Jesuits (modern Eastern Paraguay, Misiones province of Argentina and historic Misiones Orientales region of Brazil). Sechura which represents coastal desert region of central Peru. Lake Titicaca in the Peruvian-Bolivian border.
Thank to your idea of the split of the Amazon, I would suggest Ucayali River to be its own map (main tributary of Amazon river in Peru).
Buenos Aires is so big to be its own map, and most of the province is represented by Pampa map, there is a region named Ventania that it has hills and little mountains that can be split from Buenos Aires. Chubut as a map is weird, the province doesn’t have any importance unlike happens with Buenos Aires or Misiones to justify (in my opinion), also it hasn’t a biome that makes it different from Patagonia. I would say the same I said of Chubut to Tocatins but I know nothing of Brazilian geography.
For some reccomendation for Asian maps, I quote this image, which the main ones would be Pearl Delta, Fujian, Lake Baikal, Bukhara, Zagros, Moluccas, Siam and Philippines.
For Europe: Crimea, English Channel and Prussia.
For Africa at least divide the Congo Basin map with the addition of Congo Rainforest and Mayombe, and as new maps Cameroonian Highlands and Madagascar.