Earlier quoted context omitted.
IIUC, the mining operation was extremely illegal (independent of the genocide, which is obviously also illegal). It happened on Brazil's watch so it's Brazil's responsibility, but I'm ill-convinced convinced that in its absence this wouldn't continue to happen (in its absence, there's no FINRA, no organization protecting these tribes... And there are still people willing to kill for mining profit).
An organization made to help is https://amazonfrontlines.org , they do a lot work in this regard.
It's not impossible, but "holding Brazil accountable" is a strategy far likelier to succeed, I suspect.