The story has known truths and known fallacies. He has the name of the ship right and he's correct that there were salvageable anchors, winches, etc. which he could only know if he was there. He has the date of the grounding and the pigs wrong. His number of casualties is close but incorrect and he's way off on the number that were buried.
I think it's safe to say he probably saw a whole bunch of bones. Whether he had the number of skeletons right is a matter of conjecture but it's an interesting coincidence that Emily reported a similar number.
I'm not saying Jones' story eliminates the possibility that James Horne's physique was uncannily similar to Earhart's and that he survived to become the castaway of Gardner Island, but it does suggest that bodies washed up after the survivors left the are.