Which things in the manuscript can be dated?

[Koen G]

Some time ago, we gathered parallels for the crossbowman's sleeves, as well as Virgo and female Gemini's sleeves. I then put all of them together, and it appeared the dates crystallized around a few decades. The core dates for these types of sleeves largely overlapped with the date range of the vellum. On a timeline, it looks like this:

   


So now I wondered, which other things can be dated with some certainty? Specific aspects of scripts, for example? Can anything be added to the timeline?

(For clarity, I'm not talking about changes of ownership etc., rather things "inside" the MS that can be dated to some period).