One alternative would be a sort of in-kind reparations: a country like the U.S. could provide the capital and expertise to build, say, a railway in a developing country, and then leave ownership of that railway in the hands of that country's government. I don't think it's fair to criticize China for not doing this (especially when no one else is doing this, and when China has a responsibility to develop their domestic economy for their own citizens, too), but it's the kind of idealistic goal we should be shooting for.