A question on 4th edition Summae

Upon re-reading the Covenant 150 submission for ArM4 I noticed something that I had missed entirely previously... Magus Talpa of Bjornaer writes in the summer of 1228 a Muto summa of L50/Q30!

Now, I'm not concerned with the quality of the book because this, in the 4th edition, is governed primarily by an ability (scribe) that can be raised to a ridiculous degree, in this case by a charm (+20) made by another Magus. I do question, however, how is he able to write a book of that level considering his Muto score is "only" 75 without his affinity or 80 with this included. I thought that the maximum quality for a Summae was Art level / 2, as is in ArM5. And indeed it is (p.188 ArM4).

Under the "remarks" text for Talpa, his creator discusses how a specialist was able to reach level 75, hence Summae of level 50 will exist for most Arts in the Order. That number is exactly 2 / 3 of the total, and I don't think it is a coincidence unless it is a mistake or there is a detail that I have overlooked. Is there a relevant virtue in ArM4 that changes the maximum level a Summae can be written or a way to add his scribe (25) to the total of his art (75+25 / 2) for that purpose? Perhaps something in the Wizard's Grimoire?

There is the Twilight Effect (ArM4 p.183) Increased understanding: just what you might get for learning Muto from Vis. :nerd_face:

See also there:

The great magical tomes of the Order have almost all been written by magi who have undergone Twilight and have brought back insights to share with the rest.

Best check this with Talpa.

That is exactly it!

Talpa has "Increased understanding +1" under his twilight effect notes and he learned Muto exclusively from Vis.