No text, but a visual code

[-JKP-]

Can anyone really believe that the author of Tratado de Astrologia filled in all the astronomical illustrations with an abstract motif as if he were a 15th century Picasso?

Yes. That was how they did it in those days. Plus it was not usually the author who did it, it was usually an illustrator or rubricator who worked with the author or with the scribe. Sometimes the author did it if it was someone who was artistic, but that was in a minority of cases.

What common sense says and what we know about medieval culture is that these motifs are something symbolic that refers to an imagined reality: the configuration of the cosmos.

If there are Vulgate Bibles with these iconological motifs it is precisely because they also allude to the idea of the cosmos.
The Tratado de Astrologia is a key document for the understanding of Voynich's iconology. Another way of thinking is that there is an armadillo in the VM. But for that I don't waste my time

Common sense says that there are many manuscripts decorated in the same way and not every dot and line is symbolic. Some are purely decorative.

You didn't even know that Vulgate Bibles and breviaries also had those patterns, so how do you know they are symbolic? I don't believe they are. I have looked at many of them. They are decorative. It was a common way to embellish illuminated initials and the borders of diagrams.

The only place where I've seen similar shapes (scaly shapes with dots inside and a small line or point on the end) used in a symbolic way is when they are piled up in lines or triangles to represent mountains and mountain ranges, but that does not appear to be relevant to Tratado de Astrologia.