As you can probably read in the vault documents, these are mostly reports of very dubious information. They are of no value since they are at best rumors and at worst pure fabrication. I've gone through all of the FBI documents and found nothing but rumors and unsubstantiated claims; the Argentinian man you mention is only one of several people who claim that Hitler was in Argentina. But that does not mean that he was, considering that in the same compilation, you will find individuals offering information on Hitler's whereabouts in Brazil, the United States, Switzerland, Canada, Ireland amongst other places.