At least he didn’t forge something along the lines of Heaven Levels 1-3, polygamy in heaven, spirit babies, or that “No man can come to Christ except through Joseph Smith”!
That certainly would have been immediately recognized as forgery.
Investigation Discovery channel’s show “Who the Bleep Did I Marry?” has an episode about Mark Hofmann. (I saw it a couple of months ago on Comcast On Demand - don’t know if it’s still available there.)