First, the text in question is not “lost.” It is not some newly discovered work that scholars were previously unaware of.
The particular manuscript that Jacobovici and Wilson rely on was brought to the British Museum for more than a century and a half ago, and the same text has been known through other sources for centuries.
The scholarly community has been well aware of it, and translations of it in English and other languages are common.
To give you an idea of how not-lost this work is, it’s been in print for centuries, I have it in my own library, and here’s a version you can read online from a book printed in 1918.
Alright, that made me giggle….