How to decipher the MS?

[MarcoP]

Imagine we have correctly guessed how the cipher system works, then we can decode the manuscript. Yes, I agree.

I think my example wasn't clear. What I meant is that it could be possible to decode some ciphers without understanding how they work. Using some kind of pattern matching.

I think I get your point. I agree that the guess might not have to be perfect, but I think it should be quite close to give solid results, and a good deal of understanding is necessary in my opinion.
Possibly the decipherment of Zodiac 340 could apply as an example of what you describe: if I remember correctly, they made a first guess that led to extracting some fragments, and then they managed to write code to explore a wide range of more complex transpositions.
Voynichese has a bunch of patterns that typically are not language-like, so they could all result from the cipher / writing-system / author-preference rather than from the underlying text. As we know, a direct matching of those patterns to a natural language does not work. For instance, thanks to the low entropy, I think it wouldn’t be difficult to map 5/13 of the text to statistically sound English, e.g. with a verbose substitution, it is not very different from what “solvers” do (but they are happy to ignore that the remaining 8/13 of the text is off). As for the solvers, the result would not be a coincidence, but a consequence of how mappings are chosen to match English. The real work starts when one tackles the remaining 8/13. For the Zodiac, things were different, since the cipher did not show obvious patterns.