As for now I think I won't find any more relevant, online available manuscripts.
It looks there are more illustrated versions of Das Buch der Natur but you would have to physically travel to some German town to see them and I am not ready for that
It looks like the leader in production of these manuscript was well known here Diebold Lauber. He was producing this stuff almost in a factory style manner, using templates for pictures and building them from parts like from Lego bricks. It made everything faster and cheaper but less original as his manuscripts are never exact copies, yet they are similar one to another.
The manuscripts which give most Voynich vibes are exactly from Lauber. I suppose the Voynich artist must have used some version from him. It is hardly a new discovery, the links of Voynich Manuscript to Lauber were discussed many times here.
The sources say that Lauber started his workshop in 1427. Voynich Manuscript carbon dating is usually given at 1404-1438 with 68% probability range. But some observations like similarity to Taccola manuscript put it on the right side of the time period, in the 1430s or even later. So this is compatible with the Lauber connection.
It looks like the Voynich author didn't use ancient, hundreds years old manuscripts for his referrences but totally new and freshed stuff, released just a few years later.
For me it suggests some kind of student or a friend of some student. Das Buch der Natur wasn't a book for wise men, it was a simple, introductory book for young men who still struggled with Latin so the text had to be in German.