Six onion-roof towers supporting heavens

[Jorge_Stolfi]

I think both things are probably wrong, neither is literal - Building or vessel.

Well, on that diagram I see many buildings, towers, islands, walls, roads, a couple of suns, many stars.  Maybe a volcano, a colonnade, a couple of square tent roofs on pillars.  Maybe a volcano. And the whole Earth, tiny, on the NE corner.

I don't see any vessel, or any objects of the size of vessels.

Why are people so reluctant to accept those six things as towers?

I mean if you dip a toe in 15C alchemy a tower+vessel combo seeming to hold up the sky is not too hard to stumble on, it just depends how you look at what the drawer drew.

Alchemists used allegories to describe chemical processes. Their writings are largely undeciphered because the historians and paleographers who are interested in them do not know chemistry.  As a result, in spite of their good intentions and great efforts, they produce totally nonsensical interpretations, as mystical/spiritual/whatever elucubrations.  (I got to meet one such researcher in person when Rene and I visited Prague, ~2000).

Not implying it is alchemy-stuff, but I think it is more "story" than "map".

Alchemists' drawings tend to be "stories", but each" story" is probably short -- one chemical process at a time.  The VMS Rosettes page does not seem to have a "story" structure.  It looks very much like a "map" to me...

All the best, --stolfi