The claimed Voynich page

[Jorge_Stolfi]

Correct, the problem is that on the parchment treated with lime, there is no trace of charcoal, graphite, or silver

The residues left by that "poor man's carbon copy" method would be very faint, and in the end they would be either covered by the paint of completely erased.  I doubt very much that they could be detected by routine lab methods.  

Assuming that the piece is modern, the "graphite" of the pencil would be very fine graphite powder mixed with clay and some wax.  The few particles that might remain after erasure would be hard to distinguish form ordinary dust.   

Moreover, if the sample is cleaned of dust before the analysis (like the samples used in the C14 dating were), the cleaning would probably remove most of the remaining "graphite" partticles, since they would not be bound to the vellum (like ink and paint are).

there are no grooves in the characters or the drawing (the grooves are visible on the back of the horizontal lines).

So this item has scribed guide lines - on the back?  

I was told that more than one person was involved in composing the manuscripts: some had a talent for drawing (even differentiating between copyists who were skilled at drawing people and those who were only skilled at drawing animals, vegetation, structures, and text - see the "Bible of Borso D'Este"), others for writing, and the rubricators who traced the red lines for titles or individual words. But it's not a given (especially if they were lay craftsmen, it becomes very likely) that they understood the text they were writing.

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Yep.  The Rubricator of this manuscript clearly did not know a word of Latin.  The Proofreader had to fix his mistakes.
   

All the best, --stolfi