How perfect is Voynichese?

[Mauro]

It is worth noting that if you combine anagrams with substitution, you will get a fairly secure cipher, no worse than a one-time pad... 

Uh, no, not even close. A one-time pad is theorethically perfect, it's way harder to decrypt even than, say, RSA encryption. Anagrams are just moderately difficult and simple substitution won't change the frequency distribution of characters of the original language so it does not add much to anagrams.