Maroons would be a very efficient to implement minor faction that could fit an extremely broad set of maps. They could also help to fix the most inaccurate placements of minor tribes
Location: Caribbean, Hispaniola, Florida, Bayou, Carolina, Yucatan, Panama, Orinoco, Guyanas, and Amazonia
They would also fit into a variety of new maps like Mosquito Coast, Mascarenes, Maracaibo, or Liberia
Unique Unit: Maroon Guerilla
Maroons were communities of escaped slaves who hid in the forest and who would in wartime use guerilla tactics to raid the plantations they escaped from.
To capture this history, Maroon Guerillas should be stealthy skirmishers with decent siege. They could have slightly less range than skirmishers to encourage using their stealth ability to close the gap. Possibly a high attack with a variable attack rate like Oromos (it would be interesting to combine this mechanic with stealth that lets you get to the optimal range). Siege ability somewhere between a skirmisher and musketeer (to be further boosted by a tech).
Voodoo Curse - Your explorer gains the ability to sabotage buildings (Like the Tsetse sabotage card)
Creole Tongues - Technologies are 5% cheaper and 5% faster to research
Retribution - Rifle infantry gain +0.5 siege multiplier