I agree that it's always "fishy" when you hear these stories about someone finding gold bars (or any treasure for that matter) and then seemingly being unable to find their way back again, especially when there's no photos taken and no physical evidence of anything.
One thing I do keep in the back of my mind though is that I suppose if there were any stories of people finding things and actually being able to go back and find them again, I doubt THOSE stories would ever make it into the public
Another thing to keep in mind is that in both the Bob Brady and Harry LaFrance stories, most of the information is coming from people that went along on the searches for them (Tracy Hawkins and Chuck Ribaudo - through Joe), not the actual people who supposedly originally found the gold bars. That means, all you're really believing or disbelieving is the story of the searches and what the searchers were told by Brady and/LaFrance.
In essence, it's a lot like your comment about Walter Perrine - you came to believe that he was 100% convinced of the truth of his mother's story. It's quite likely that Chuck Ribaudo and Tracy Hawkins were 100% convinced of the stories they were told as well - it could well be true that NONE of the gold bar stories are true - who knows. Heck when it comes down to it, even if someone produced a gold bar or a photograph, I'm not sure I'd be willing to bet my life it wasn't a hoax.
I think "The Sterling Legend" originally came out in the early 70's - I don't know if her comment about the gold bars being found in the 1940's was in the first edition or not, but even if it is, you're right that it would still have been after Perrine's story - even though her claim is that the men found it in the 40's.
Looking forward to hearing Walter's story.