The reviews were wrong.
There is an interesting understory of how Jesse James (all THREE of him!) worked for The Knights Of The Golden Circle to increase the hoard, but the majority of the (so claimed) vast fortune buried from Georgia to the Superstitious Mountains was from the removed Confederate treasury.
You ain't the first person who wondered where it went.
Of what is there the CSA treasury is indeed the likely source. There is a lot of gold from that era reportedly remaining unaccounted for: gold from the New Orleans mint, gold from many of the Jesse James and other outlaw train and bank robberies, the personal gold holdings of the wealthy in the CSA government. Much of it dissappeared during and after the war with very little record. Some of it probably went to Britain, where several of the CSA officials, senators, and representatives who escaped the invading feds stayed for the next decade. And yes, some of it was indisputably buried.
Accounts abound of southerners gathering up all the gold and silver in the plantation house when the yankees were approaching and burying it in the woods so it wouldn't be stolen and plundered. Some of that is without a doubt probably still buried out there.