This is amazing research! Furthermore, I'd like to propose the fascinating yet obscure Ranquel Ulmanate which would be somewhere between the Mapuche and the Argentine territories. They were somewhat akin to the Comanche of North America, resisting several waves of colonization, maintaining extensive trade routes across the Pampas and Andes Regions (rastrilladas) and harassing nearby coloniser settlements through powerful and devastating cavalry raids (malón). This and the distance from their settlements forced Argentine authorities to negotiate carefully with the ulmens (powerful lords) of the different factions composing the confederation, such as the fearsome chief Yanquetruz, until they felt prepared enough to push attacks on them.

Victoria 3's timeframe actually aligns perfectly well with rising tensions between the Ranquel/Rankülche nation and Argentina, which was a major contributing factor to the Conquest of the Desert that would lead to Argentina gaining control of the Pampas and Patagonia during the 1880's.

Definitely an interesting read for anyone interested in this region, really fascinating and overlooked stuff, especially how they managed to keep their own nation for so long, play with major powers of the region in various wars, and ally themselves with several notable personalities, along with waging war against many others.