How perfect is Voynichese?

[ololololo]

Anagrams blur the statistics, making it impossible to detect substitution. If letters are encrypted with numbers, and numbers are encrypted with other symbols, the resulting anagrams will be completely unanalyzable.

Anagrams over simple substitution won't blur character statistics, so it's still relatively easy to break, if the language is known.

Yes, but not always. It depends on what substitution we apply. In the case of VMS, for example, knowing the language won't help us much.