Several nationalities in game are currently unused and are thus available for modders to create new countries without disrupting the base game. I used these extensively in Alternate Empires.

Ghana, Pakistani, Lybia; not found in events or in use in existing governments or events and thus can be edited at will.
SW Chinese, North Chinese, Hui(chinese faction) Except in Armistice and Carnage these factions are not used even through events.
South Chinese and Xiang Chinese also don't occur through events however these use nonmandarin cultures so I added them onto the map.

North and South Rhodesian are also not in use by default (as the Rhodesias just use regular Rhodesian) I used all 3 Rhodesians and Nyasalander for SAE.

Atlantic Islander and some other nationalities only represent small populations the former of which I replaced and used.

Hyderbrad and Rajputan are only used for some protectorates in India but aren't on the map so can be replaced and edited.

There are also many unused ethnicities; Italian, Han, Brazilian, Afro-brazilian, Somali, Arab, and many others that are easy mod material.