Whatever the Watchtower said in the nineteenth century about race , it reflected the prevailing viewpoint of its time. I am not aware that it advocated segregation but in areas where that was necessary to avoid a backlash, it went along with it .
In South Africa in my memory their view was that the preaching work was all important and not to be sidetracked by local inequalities. They did a work-around and had black and white congregations.
I am not saying that was good or bad, but that ipwas their judgement and they mixed as soon as the law allowed