I had a look at the manuscript for a while and found it suspicious how tightly packed the writing was against the illustrations on some pages. In common language words and letters vary in width, so when you approach the end of the line when writing, you naturally insert a break to begin a new word and avoid overrun. The manuscript is missing these kinds of breaks - I saw many places where it looked like whatever letter might squeeze in had been written at the end of the line.

I wanted to do an analysis of what letters occur just before/after a line break to see if there is a difference from the rest of the text, but couldn't find a transcribed version.

My completely amateur take is that it's an elaborate piece of art or hoax.