Voynichese is a numeric cipher?

[ololololo]

but how much time will it take to find the correct decoding?

Well, I just guessed the words I saw. Of course, the phrase doesn't make sense on its own, but the words were still guessable. My goal was to solve the anagram...
Plus, I did it at speed to see how quickly I could see the words. 
Either it's a problem with the algorithm, or I'm just not paying attention. I don't know what else can be made out of VROE, for example.
However, I wouldn't say it was difficult (at least I quickly guessed the words, even if they were wrong).
Neither the first nor the second stage of decryption is particularly difficult, but it does take some time.
It's worth trying to "torture" other users in this way to understand how it works for them, not just for me.
I don't think my "efforts" will really prove anything to you (at least it will always be a little easier for me than for others )

P.S. It would also be more reasonable for you to try to see if you can use this cipher yourself (i.e., if you can encrypt text, find letters, assemble words, anagrams, etc.). It's just that if I solve the anagrams incorrectly, I don't know what it will prove. If I don't solve them, perhaps another English speaker will solve them correctly...