Why the month names aren't Voynichese?

[Jorge_Stolfi]

One of the two aspects of Dunning-Kruger is that the dillettante is likely to massively underestimate how much there is to know about any (epsilon) topic. ... I can happily accept that knowledge exists (because it has been gathered and improved over generations of specialists) in which I have no insight whatsoever.

I agree that specialists usually know much more than a "dilettante" can hope to learn from the internet.  

But I know also that there are many specialists who know much less than what they think they know, and will categorically emit opinions that are flatly wrong. 

And there are also some experts who will categorically state some blind guess as if it were certain, instead of honestly saying "I don't know".  Because saying "I don't know" is not good for one's reputation as an expert...

But, fortunately, for each expert there is always some other expert who will categorically state the exact opposite opinion.  So we always have the choice. 

But anyway, my question still stands.  Did handwriting and book binding really change completely, all over Europe, at the same time?  Is that "15th century" assessment for the handwriting of the month names specific to Germany, or good for all over Europe?

All the best, --stolfi