I suppose the state of Brazil is something that could be considered a settler colonial project and with it's continued existence this sort of thing remains doomed to happen.
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).
In the absence of a Brazil, that work would have to include force projection. Do they have any experience hiring private military groups to protect the interests of the indigenous people they safeguard?
It's not impossible, but "holding Brazil accountable" is a strategy far likelier to succeed, I suspect.