Voynichese is a numeric cipher?

[ololololo]

Like I am convinced that the Earth is round.

Well, I’m completely sure that the Earth is round. I don’t prove to flat‑earthers that it’s round because I don’t see the point. In this case, there’s no need to even appeal to any scientific evidence.
You’re trying to talk about China almost everywhere, and the only evidence you have is the Red Rooster recipe. It would be more interesting to hear about other recipes and statistical comparisons between the entire SPS and SBJ texts than to rely on the unprovable theory of the Chinese dictator (I remember that it’s just a hypothesis, but you cling to it as if it were flawless, even though you could find a wealth of contradictions).

a codebook cipher

Purely theoretically, it’s possible to use it. The question is how one can even create a book cipher for a book of that size, and make it work flawlessly. So I don’t believe in it either.