i saw a great explanation how it was made in a documentary i can never track down again cuz the internet is terrible now. it’s been a long time since I saw it, but the idea was they basically wrote letters on the page using some form of stencil to give the “illusion” of real, unknown words as opposed to strings of random letters. they recreated a little and it looked essentially the same. throw some illustrations of plants and stars in there, and bam you get to sell people a mystical mysterious book of knowledge