The vowel exchange "a" to "o"

[Jorge_Stolfi]

However, the exchange from a and o unfortunately does not behave like in your Arabic example.  However, the trend with prefixes and suffixes is also recognisable to me. Have you already found words that might make an Arabic origin more explainable?

I don't think the language is Semitic (Arabic Hebrew, Ge'ez). I was just giving an example of a language where letters anywhere in the word can be changed while preserving the basic meaning.

The drawings are not exactly typically Arabic or oriental.

Indeed, the vellum and writing instruments are European, the character shapes, writing direction, and parag layout are European, the nymph hairdos and hats and (rare) dresses are European, the castles are European, the Zodiac sign icons are European ... But that only shows that the Scribe was European.   

On the other hand, the absence of any recognizable European symbols or diagrams (alchemical, astrological, kabbalistic,  religious, etc.) suggests that the ultimate origin of the contents is not European.  Even the depiction of the Zodiac as 24 x 15 = 360 "things" is not a common European choice.  If the person who hired the Scribe was European, he must have been taking the contents from non-European sources.

IMHO, the assumption that the Author was European and the language was "European", just because of all those superficial elements are Euroepan, is the basic fatal mistake which has prevented any real progress in the decipherment for the last century. 

I think that old Baresh, writing to Kircher, was closer to the truth than practically all the Voynichologists who came after him.  Starting with Raphael Mnishovsky...

All the best, --stolfi