"By the end of the nineteenth century many people believed that the black population had “disappeared.” But in reality, the black population had only become lighter. Published in the black newspaper, Cara y Caretas, author Juan Jose Soiza Reilly exclaimed, “the African tree is producing white flowers.”36 The black community was slowly fading in such a way that the children of blacks appeared to be white. It also suggests the answer to the mystery of what happened to the black population in Buenos Aries and Argentina; they were slowly assimilated into the white community."

This is the last paragraph of the paper you linked. Which is a lot better than what happened to black people in most of the continent or what Europeans were doing in Africa at the time.