But that need to be said with some tact because while it's good, it does not by itself right past wrongs. The gross part is reducing it all to just a "White" story with no agency granted to everyone else (though ironically, some of the most virulent voices claiming to speak for the oppressed will do just that).

Ya, that's the point I was trying to make and you said it better. I meant that (certain groups of) white people go under-credited (in lefty circles) because it's hard to state without seemingly turning it into a white man's story. I think this self-reflection and criticism is an important aspect to a lot of social changes and should be part of the open narrative. I also think it already is part of the narrative for a lot of left white people, just not openly talked about which is not good for a lot of reasons.
Since you mentioned it, I think this is separate from the issue of righting wrongs, which is also super tricky though - you can have a story that says that people both benefited from something terrible while were also actively trying to fix that thing. The fact that there were white abolitionists and that now no white society will tolerate slavery (as it was 150 years ago) doesn't right a wrong and it never will if you think of righting a wrong in a complete sense - rather you can see it as righting the wrongs that may have been done to people hypothetically had slavery continued.
If you think about it in terms of righting wrongs I think it leads to a strange perspective. Like you can say that all white Americans benefited, and still benefit from slavery (and really Canadian's and Europeans as well) and thus have some kind of culpability but in a lot of ways that culpability is very indirect. This leads to the question, so at what point does a change in their beliefs or actions overtake their culpability? I'm not sure that's a valid question. A specific example of this would be that anti-slavery sentiment in the UK made it so that politically the UK couldn't enter the war to help the confederates. To frame this a question about the UK righting wrongs is not valid yet I think its an important part of the story (and the fact that you can say that white people in the UK prevented white people in the UK speaks to the fact that white people aren't really a homogeneous group*). I think there is a comparison to be made with climate change where everyone one is a sinner but don't have the thought right now.
*For example, the French have 2% extraterrestrial DNA.