Looking closely at the places where the spirals cut across the waves on f68v3, one can see that the waves are behind the spirals and only partially hidden.
Using Paint.NET I have drawn in the covered parts of the waves and counted them, adding a number to each wave. The result is 43 waves.
A number was added to each wave on the d’Oresme diagram. The result: 43 waves.
This makes the possibility of a coincidence rather remote.
Here are the two overlaid:
Ellie Velinska pointed out a drawing in Nicole d’Oresme’s Livre du ciel et du Monde (1377) that looks very much like the “nebula” on f68v3.
The VMs is 23.5 x 16.2 cm, while the d’Oresme book is 27.5 x 19.0 cm.
I trimmed the excess and resized both the page and the folio so they’d match scale.
Overlaying the d’Oresme page, I had to enlarge it to 48.2 x 33.3 cm, or 2.0x the Voynich to match the sections.
The lines and circle and words in the middle T-O map match up, as well as the “waves” at the outer edge of the blue field with stars.
I conjecture some type of projection mechanism was used to copy from the book.
It’s hard to find the right transparency level so both drawings are visible, but sharpening the d’Oresme overlay makes the matches clear. This is a replacement for the first picture.
For comparison, here are the two separate images, not scaled.