I don't know this cheering to the killings of whites, thread. I am not cheering to that, and I didn't like the movie if you are referring to that either.
It's been called racist by black and white artists everywhere.
I am not aware of what you mean by that example, I came here to see the homecoming queen.
As for historical accountability: You raise some important questions. I don't know the answers to all of those, but what I know is your answer is no answer either, that is, the "guilt" or the "accountability" fizzles away exactly when the generation who was responsible is renewed by their sons and daughters.
My guess is, it's somewhere in between. There's a time constant that takes some time depending on the severity of the crime. Remember: On an international law level, Germans are still accountable for the Holocaust.
As an individual, "Danger" isn't guilty of any crime, obviously. But as an intellectual, you have to be aware of recent history and the crimes committed by a category of people to one another. You happen to be white, so you belong to that category by loose association. It's not like you could be tried for what they did, but you are (as an intellectual), expected to show at least an understanding of what a lot of black people may feel about the issue.
It is the oppressed that remembers bitterly, not the oppressor. That's why it becomes more offensive and this is a de-facto civil right issue if elements of racism are found in this distasteful homecoming choice.
Whites can point out racism, too. In fact they do, and -at least- I am not saying it's whining.
What I am saying is you are choosing a wrong example to point out your truth.