The nymphs are possibly inspired from Dante manuscripts

[Bernd]

If you asked people today to draw from memory a detailed picture of some plant that is supposedly well known -- like a dandelion, a rose bush, a carrot or corn plant, even a palm tree -- eight of ten of the results would be as flawed as the VMS plants. 
Our memory is a bizarre tool.  You think you can see in your mind a perfectly clear image of the staircase in your home, or the building of your school, which you have seen thousands of times from all possible angles.  But try to bring up that mental image and count the steps in that staircase, or the windows in that building. You will find that you can't. (Unless you are one of very few people with "photographic memory".)  And it is the same with other objects, like plants.  

That's certainly right to a degree, but there are limits. You wouldn't draw a looping in the staircase because you know that's not how things work. People inherently know that plant stems do not branch and fuse creating loops. You find the oddest plants in medieval herbals, because imagery was often derived from the description an the artist had never seen the specific plant IRL. But with very rare exceptions for specific reasons like the You are not allowed to view links. Register or Login to view., you will not find stem loops and fused plants like in the VM. If this was an isolated case, one might argue this was just the artist's style, but it is not. Root tables are another such case that are probably derived from plants drawn inside a pond or on a patch of soil like in some Dioscorides copies, which the VM author just misunderstood.

[DG97EEB]

I don't think the smoking gun exists. You would have to be extremely lucky and it'll happen by accident most likely.  I think the best we can do is try and nail down a source ecology and get everyone to agree it. I think given the number of different opinions out there, that itself is a challenge. For example, if I said the following, which GPT has summarised for me based on a year of work on this, I'd want everyone to agree with it. That would actually be progress. It doesn't solve it in an absolute sense, but it would be a framework at least:

"MS408 was probably produced c.1415–1445 as a deliberately planned, modular scholarly manuscript by a small coordinated group working within a shared textual/graphic convention. Its production was organised unusually strongly around the physical bifolium: scribal ownership repeatedly follows conjoint parchment sheets rather than normal sequential copying through a gathering, a pattern that now looks genuinely atypical against structured contemporary controls.

 The surviving codex is therefore better understood as an assembly of separately executed physical task-packets than as an ordinary serially copied book.

Its parchment provides an independent material signal. The near-equalisation of hair and flesh sides is substantially closer to late-medieval German/HRE preparation practice than to ordinary Italian parchment, while the best historical mechanism evidence shows that such parchment could enter northern-Italian book production through transalpine suppliers, preparers, cartolai and migrant craftsmen. Thus the manuscript need not have been physically written north of the Alps: a northern-Italian production environment using transalpine-prepared or transalpine-style stock is a coherent and increasingly attractive model.

The intellectual content appears compiled rather than derived from one exemplar: medical, botanical, pharmaceutical, astronomical and cosmographical materials draw on both Italian and Germanic/transalpine traditions. Illustration and colouring were at least partly separate production operations from writing. The comparatively planned execution and sparse authorial revision argue against the surviving codex being a rough notebook; a prior accumulated scholarly corpus followed by organised reproduction is a better fit.
The strongest social model is therefore a small scholarly or academic circle—possibly student-associated, possibly a private practitioner/scholar network—working under an organiser or shared project convention. Padua/Pavia and the wider Veneto–Lombardy academic corridor currently provide the richest exact-period ecology for that combination of transalpine personnel/material movement and northern-Italian medical/astronomical culture, but neither the city nor the social identity of the group is identified.

Voynichese itself remains causally unidentified. It is clearly a highly constrained shared writing system with strong local production state, but current evidence cannot distinguish meaningful notation, cipher/realisation, exemplar-guided regularisation, or sufficiently sophisticated generated text. Provenance before the early seventeenth century likewise remains unproven"

Now if I provide a body evidence that objectively supports that, then that would be progress....

[eggyk]

Imo, if there was to be any smoking gun that exists within digital libraries, it would be one of the circular astrological diagrams. There are plenty of weird and unique diagrams similar in their weirdness found in a wide range of manuscripts, and it is entirely conceivable that due to those works being written in known languages that they do not raise a red flag for being mysterious.  They are simply marked as something like "astronomical diagram to track phases of moon(?)" and then moved on from. 

As for nymphs, a smoking gun would have to be a drawing matching an entire scene: matching the amount of nymphs, their body positions, the things they hold, as well as the same buckets, baths or pipes. But that would be much more likely to have been spotted already, I would think.

[Oscroft]

I will add that hands are a detail that notoriously requires some skill to be drawn accurately.

Yes, hands can be really tricky to get right...