Discussed earlier in the timeline. Europe is a third world shithole in this timeline so poles living in one of the most prosperous areas in the world have little incentive to go back.
Most mods add at least the west African kingdoms and the kingdom of Kongo. Some add the rest of the Congolese kingdoms too. NNM has the most African states represented with HPM trimming it down some.
Though note that this was not atypical among the colonial powers. I was surprised when I learned how often chemical weapons were used in suppressing colonial revolts post WWI.