Point of advice for filmmakers young and old -- heck point of advice for anyone who seeks to "give voice to the voiceless": the "voiceless" have a voice, don't speak for them, but allow them to speak for themselves.
In making The River Jean Renoir made one very good choice: he hired Satyajit Ray as a local expert. The work here later helped to inspire Ray to make the Apu trilogy, but first off it allowed Ray to suggest that maybe if -- like Renoir claimed -- they were to make a movie that actually respected India and it's peoples, they should include some of those peoples in major roles. renoir agreed! And added one principle female Indian in a story about an aristocratic family of white British people.
When you have a pedestal and wish to raise someone else up, do what Brando did with Sacheen Littlefeather: use your name and clout, but step back and let the people you claim to represent tell their own story.