A key to understand the VMS

[-JKP-]

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I agree though that this may not be enough to explain Voynichese. If you consider other factors though, it may explain some things. Like if the one who converted it to script may not have been a native speaker and oversimplified and overstructured things.

I am completely open to this possibility, have considered it, in fact. I think it is possible that someone could transcribe something and not know what matters and what doesn't.

For example, someone born to a western language, where a "g" can be written with a tail of any length without changing the letter's sound or meaning, might not understand that in some languages, the length of the tail or even the presence or absence of a serif, denotes a different glyph. Thus, information would be lost in a transcription.

This might account for some of the apparent repetition, but... it still doesn't explain the positional inflexibility. In most languages, most letters can be used in most positions, not always, some languages have certain letters in certain places more often than others (like a "u" following a "q" or "h" following "t" or a vowel following a consonant in a syllabic language), but the rule set in Voynichese is so strict that even over-simplified glyph shapes can't account for it, and rules for initial/medial/final letters aren't enough to account for it either.