Watch this video, especially starting around 2:30.
Notice, they don't even quote Joseph and Oliver:
There is a direct conflict between these statements and the statements about the stone-in-a-hat.
The revisionist Church historians choose to disbelieve Oliver Cowdery.
Some people choose to disbelieve the stone-in-a-hat statements.
The obvious way to reconcile the accounts is that Joseph used the stone-in-a-hat to demonstrate how the translation worked, not that he was demonstrating the actual translation.
I discussed this here: