Writing an Affidavit for my clients Asylum application. Through extensive interviews I have a fair amount of information, but have been unable to find any information on line/in libraries on the Bashi or Shi tribes of the eastern Congo.
Might want to try /r/askanthropology
Just looking briefly, there is a fair amount of anthropological work out there. Here's one article that might be of interest or start you down the right path. I agree that asking in ask anthropology or posing some more specific questions is likely to get some results.
I know of a historian who now and again gives testimony on behalf of asylum seekers from Zimbabwe via Amnesty International. I'd imagine there is a fair chance Amnesty has a person who speaks to the needs OP outlines, though I don't know that.