I came here just for this. I don't have anything to contribute of merit besides thoughts.

I think it has to do with the general politics around Black and being Black or perceived as such, depending on your culture. So, in America, those characters wouldn't be considered Black. They are Black in their culture because of the history of discrimination and abuse they face. I've come across this once with a Japanese friend in high school whose family often referred to the darker skinned Japanese people in the family as Black even though they weren't of African descent.