So Waine, it would be a miracle if there were no wrong info in Forton's work, and you may bet that your compadre's acquainted Italian experts will not be the first ones to exclude imprecisions in their work as well. Have you had a look to Forton's work? the bibliography he has consulted counts no less than some seventy six authors/works ... two, being Italian.
Indeed Forton's work has not been translated but, neither was that of the Italian experts. And Forton's so far had a third edition published ... 'corrected and augmented'.
My knowledge of navajas is nihil; i am more focusing on the certainty with which some folks determine that the other guy's work has flaws, letting transpire that theirs is perfect ... as opposed to the old saying; my neighor's hen is (always) fatter than mine
It will be interesting to check on that example you talk about, to see whether that navaja was made i don't know where and later had the Sevilla dedication added.