Simple. Joseph made it up. Or wrote what God inspired him to write. Whatever it was, it wasn't a translation of the scroll.
It wasn't a translation from the materials we now have, that's pretty much a settled issue. The real issue is what the text actually says, and the parallels within that text to what numerous ancient texts, now available but unavailable in Joseph's day, also say...about a number of interesting things.
But harmony cares not to pursue a knowledge or education in these matters past Brent Metcalf's facile forensic dabblings.
How do you explain the Book of Breathings (Hor) text that has been canonized in LDS scripture? Is the Book of Breathings scripture?
EDITED:
The BoB text that was included in the PoGP is the direct link to Hor's Breathing Permit.
"Sire, I had no need of that hypothesis" - Laplace
The people of the City of Enoch taken away by alien beings from kolob?
The Book of Abraham was translated correctly by Joseph Smith who was the only one on Earth who could discern the actual writing by the hand of Abraham himself on the scrolls. Spiritual translation that mere mortals cannot even see, much less translate. Thus are the real mysteries of the Kingdom preserved from the fools who pretend to be learned but are in reality blinded by the sophistry of man as guided by Satan!