Grishka wrote: It is good practice that fragile objects are not lent to every PhD student.

Oh, absolutely. I can cite far too many examples of works being ruined by overuse. But it does make it hard to do research.

Dating is important, but what is even more important is the question what happened in what sequence, and why.

The why is the whole issue here. :-)

But the dating is very important in this case -- if the date is c. 1325, then the experience of the scribe with this new-fangled notation is an issue. If the date is c. 1400, then the newness of the notation is not in itself an issue. And while I am not a paleographer, and have not seen the manuscript, I agree with those who say that the hand looks more typical of later Latin hands. (It it absolutely not typical of English writing of the period, which is prone to big Anglicana loops.)

I'm not saying that sequence doesn't matter; I'm just saying that the issues look different depending on the MS. date.

I'd frankly like to see someone radiocarbon date one of the flyleaves.

Long ago, someone quipped "Egyptology has the advantage that our imagination is not limited by too many facts." That was before the Rosetta Stone.

Yes. As their interpretations of hieroglyphs clearly demonstrated.