What do you think the six objects in the central rosette represent most likely?

[Koen G]

If the pigeons got together in a council, then this structure must be where pigeons were imagined to live. A dovecote or columbarium, could be tower-shaped:
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[Koen G]

Is it a cannon? Is it a microscope? No, it's a dovecote!

   

From the Très Riche Heures, 1416. You are not allowed to view links. Register or Login to view.

[nablator]

The top part is like a tower. But the lower part... Not a very good pun on columbarium / ciborium is it?

[Koen G]

The top part is like a tower. But the lower part... Not a very good pun on columbarium / ciborium is it?

Just at first glance, I think the resemblance between the ciborium and dovecote might be coincidental. As the history of Voynich research has shown, there is often a parallel evolution in cylindrical objects. Cannons, microscopes, towers, liturgical vessels, pharmaceutical vessels... Similar elements often return.

I wonder if the Holy Spirit lives in a columbarium. Probably not

For the columbarium in the manuscript illustration, I think they want them to look like a human building for decorative purposes, but then put it on a pole to get it higher up. The pole is there because the bottom part of the tower is useless for the doves, so you automatically get a little house on top of a pedestal of sorts. Only when it's a really big (expensive?) columbarium, it will be a full tower so people can actually go in and climb up to where the doves live.