So when does reparations end? Is there some objective condition that can be met where we can all agree to stop trying to prop certain groups up while discouraging others?

I personally don't think that's possible. We would spend the rest of time trying to correct perceived wrongs done to categories of people for hundreds of years. It's far more sane to simply agree to NOT discriminate based on race/gender/creed/religion/politics OR say that it is fair play to do so.