[split] Designing the glyph system

[Jorge_Stolfi]

Depending on what you mean with layman, but in my understanding of the 15th century society, the creator of the manuscript writing system had to have some qualifications and knowledge that were not at least so common in that era.

Well, yes.  But the required knowledge is not that great, and many middle-class people would qualify.  Like Marco Polo and his uncles.

The creator of the manuscript's writing system must have been well educated in Latin to scribal proficiency

There are bits of evidence and common-sense arguments saying that the Author who composed the text and conceived the basic design of the diagrams was not the same person as the Scribe who actually put pen to vellum.  So we have no information about the scribal abilities of the Author.  

The glyph shapes may resemble those of Latin letters at first sight, but that impression quickly dissipates when one looks at them more closely.  Voynichese glyphs were mostly created by combining a set of half a dozen simple strokes like e, i, ' in pairs in almost all possible ways.  One reason for the superficial resemblance with Latin letters is that both were designed to be written with a quill pen, which led to the simplest strokes having similar shapes.  

Only three letters of Voynichese -- e, a, o -- match letters in the Latin alphabet.  Voynichese r is clearly different from Latin "r", especially in the way the latter was written back then.  Voynichese i is always dotless and slanted NW-SE, whereas Latin "i" is supposed to be upright and often needs the dot.  Voynichese f always has a loop at the top, very unlike Latin "P".

Another reason for the superficial resemblance of Voynichese to Latin script is that both have (1) short "minuscule" symbols, some with ascenders and descenders, and (2) tall "majuscule" symbols with no descenders, resting on the same baseline.  But feature (1) is shared with other scripts like Greek, Armenian, Georgian, Cyrillic,etc; and several of them have also (2).  Anyway, the tall glyphs of Voynichese seem to have very different properties and uses than the majuscules of other languages.

In fact, a notable feature of the Voynichese script is that it has no significant resemblance to any other known script.

and schooled in its inflectional grammar, such that the stem-and-ending structure of the word functioned as an internalized model. ... He also has to have had exposure to at least one, but possibly more, non-Latin scripts and languages like hebrew ( final-form allography, root-and-pattern word-model), sufficient to derive a structural features from them.

The words of Voynichese have a rather rigid structure, with multiple slots (10 or more) each of which can be left empty or filed with one of a small number of alternatives. 

This structure does not resemble that of words from any "European" language, including Hebrew and Arabic.  All attempts made in the last 100+ years to match those words to those of "European" languages, or to deduce the grammar of Voynichese, have completely failed.  

Those who still believe that Voynichese is an "European" language are forced to admit that the the whole VMS has been encrypted with a complex cipher that completely obscured its original lexicon and grammar.  

Thus, in particular, we have no clue favoring any particular "European" language over any other.  The few parts that we can read -- the folio and quire numbers, the month names, and the "marginalia" -- were most likely added after the Author was no longer around; and the last two seem to be in two different languages.

Possibly also further trained in the positional numerate tradition of commerce

No one has been able to identify any "words" that could be numbers, either.  So we don't know anything about the Author's mathematical abilities. (But we can see that the Scribe did not know Euclidean geometry at all.)

He possessed some knowledge of an astro-medical practice — herbal, pharmaceutical, calendrical, balneological, and gynecological

If the contents of the VMS is original material from the Author's mind, yes, he must be a polymath.

But the Author may have simply copied or summarized existing books, translating them to Voynichese.  In that case, he may have known as much about those subjects as the scribes in monasteries that produced all sorts of treatises for sale or commission.  That is, maybe even nothing at all.

My conjecture: To encode their original source text, before the creator designed the glyphs, he did estimate how many glyphs were needed to produce the desired result.

That seems to be a very safe bet...

Another conjecture: What he did is possibly a lossy encoder, not encoding everything, but an intended receiver is able to recover the missing information

It is highly likely that he left out some details of the original text as it would have been spoken by someone who knew it and its meaning.  Every script, even the ones that were created or reformed in modern times, is "lossy" in that sense.

At a minimum, he probably did not bother to record pauses and rhythm, including the pauses between sentences.  Few scripts bother to indicate the stressed syllable in a word.  Many use the same letter to indicate two or more very different sounds.  It would be remarkable if Voynichese did not have such "features" too.

All the best, --stolfi