In the case of the paintings & copy of the Constitution, there is a provenance of sorts... historical documents. Once the item is authenticated, then you where it came from.

The Nazis stole anything & everything of any value... the valuables & gold "recovered" from the concentration camps is a gristly tale. Only a pittance of their loot found its way back to the original owners or their surviving family members.

To be honest... I'm more repulsed by the destruction of "artifacts" and cultures by intolerant zealots - religious or otherwise- bent on imposing their beliefs on others. The Spanish missionaries who destroyed anything that they felt was a heathen reminder of non Christian religion. The defacing of church artifacts by various communist groups. The list goes on...