> This is an "easy to say, near-impossible to do" task that's been shoved with little effort from the proposer onto the museum staff.
In principle, this is true, but in many cases the responsible party is very well-known and yet there is active resistance from the British Museum to repatriate the plundered items. For example, the Parthenon Marbles.
According to Wikipedia, the Parthenon marbles in Britain has been repeatedly asked (by the Greek government, then by UNESCO itself) to be returned to its original Athens, Greece location. They were literally taken out of Greece by an Earl of England claiming (with no paperwork!) authority from the empire occupying Greece at the time.
There is a literal museum in Greece containing every part that wasn't stolen this way, in their exact original placement, waiting for the stolen pieces to be returned to complete it. And the British are still resistant.
For example the Koh-i-Noor diamond passed through many hands, often through conquest. And perhaps the ruler who originally owned it didn't obtain it through entirely fair means.
In principle, this is true, but in many cases the responsible party is very well-known and yet there is active resistance from the British Museum to repatriate the plundered items. For example, the Parthenon Marbles.