Budza a.k.a. Buja, Embudja, or Limbudza is a Bantu language spoken in the northwestern DRC. There are several other languages that are supposed to be closely related to it, mostly (or all?) spoken near the area where Budza itself is spoken, but I haven't found songs in any of them yet.
This is a song called "Ajuba" performed by Budza soldiers in the Force Publique, i.e. the colonial army in the Belgian Congo. I'm not 100% sure it's in Budza, but I think there's a good chance, at least:https://www.youtube.com/watch?v=RiSFWQ0QLwY