No text, but a visual code

[ololololo]

I agree with you that the folding folio with rosettes is a cosmological model of the universe. Does everyone agree?

The answer to the question  "[something about the Voynich Manuscript], does everyone agree?" is always "no". 
If you're lucky, you'll get a "yes" on "does anyone agree?"

However, this also applies to the official classification of VMS into Herbal (Botanical)—why is it called that?—and Balneological (Biological)—why use this name when there is no generally accepted definition? Why "Pharmaceutical"—who agreed on that? And I certainly don't understand the category "Recipes"—is that generally accepted, too? And for what reason?

These are conventions.
In Botany, we see drawings of plants, so we call this part Botany. We don’t know whether these are actually plants or not.