Well, for starters, the fact you think that children being pulled up on using hateful language is a bit of an indicator, isn't it?
What that indicates is that some children will go to school with the expectation that they may be treated badly. Then other children will be appropriately 'pulled up on it'.
Yes, of course it's good those children are pulled up on it. But that doesn't mean the original hurt isn't there.
An educational institution needs to take more responsibility for tackling these things head on, for doing everything possible to ensure children never get to the point of being exposed to hate speech.
I think the shifts in education will come alongside shifts in society.
I work in HE and there is quite definitely institutional racism. People talk over black women in meetings. People assume the black lecturer is the cleaner. People tell black students 'oh, are you here for the postcolonial lit module?' or 'I wouldn't think you would want to study this'. Primary material by or about people of colour is still not often enough on the syllabus; scholarship by scholars of colour is still not often enough on the syllabus. We have a woefully tiny number of black professors, and black academics in general.
All of that filters down, IMO. You want your GCSE group to be exposed to good, interesting perspectives on a subject, developed by black academics and about black histories or people? Good luck with that. It's not impossible, but your choices will be fewer.