Have none of these found correspondences proven to be applicable even to the mixed Latin-German BGL text? Because these words were given in Roman letters anyway?
Unlike some ancient multilingual decrees such as the Rosetta stone, even the one Voynich page that has other languages isn't simply the same thing written out once in each language start to finish. It's four lines, with a bit of space between the first and the other three. The first two words of the fourth line are the only ones in the Voynich alphabet. How they relate to the rest of that page is unknown. The first one matches the word for "juniper". The second is something that recurs many times throughout the book, often more than once on the same page.
since no Voynichese has been recovered from either the BGL text or any other part of the book, it is hard to see how any decipherment can be said to have been achieved at all... I don't think it can be shown that any progress whatsoever has been made.
These sentences are pretty similar, but with one spot occupied by "decipherment" in one case and by "progress" in the other.
If you meant the same thing both times, then you must be equating those two words, in which case that's the problem right there. Suddenly entirely deciphering the whole thing all at once is not the only kind of progress. It's not even a kind of progress that actually even
happens.
If you meant two different things by those two word choices, then I'd agree with one and not with the other: there's progress, but not decipherment, because the progress that's happened so far is like with hieroglyphics between 1802 and 1822, the stuff that must happen
before decipherment. I still don't get the source of the dismissiveness of the progress that leads up to deciphering as if it were not nothing at all. Could it be caused by an impression that the names of plants are supposed to be coming
from the letter-sound associations (in which case the letter-sound associations would have come from nothing)? They're what
led to the letter-sound associations; they're the "Ptolemy" and "Cleopatra" of this book, because plant names, like the names of famous people & places, tend to be very similar across multiple languages.
What does capturing the phonetics do for us when the ultimate goal is to decipher meaning?
Um... sounds carry meanings in languages. In languages, meanings are carried by sounds.
My skeptical bone is telling me one may not be able to determine the difference between nonsense and a sufficiently unknowable language. How far off is my bone?
Bull's eye. One statistician runs some algorithm and says it can't be a real language, another runs a different one and says it is. What that means is that they don't have a reliable method of getting an actual answer on this subject either way... which is no surprise given how few precedents there are to base such a method on in the first place.
But when symbols are found repeatedly showing up in the right places to represent the same sounds each time, like P, T, & L in Ptolemy and Cleopatra, there's no need to resort to those kinds of indirect inferences. Then the phonetics are just a plain fact right in front of our eyes, so still calling it random/fake instead of a true alphabetic system becomes a case of desperate clinging to a pre-evidence idea (no matter how reasonable it was to speculate either way before when speculation was all that could be done).
It would help me if you could draw a parallel between what might be happening here and, for example, "decoding" whale song. (Aside from the fact that we have living animals to interact with.)
I don't know of anything comparable about it in any way at all. What whales do probably isn't even a language, nevermind a written one, and we have no prior experience with any other whale-song-like thing (whereas with human spoken & written languages we can base our procedures on prior experience with other such languages).