Cipher or unknown language - historical perspective

[Jorge_Stolfi]

With my somewhat limited (but nonzero) experience with the quill, the below seems to me to be the most likely way the letters in my image above were penned (quilled?):

I agree with most of your "diagnosis", except that I believe that the plumes of r and s were drawn the other way - starting at the top of the i and moving up, with light pressure.  

The plume of n is definitely drawn this way, except that it starts at the bottom of the i. Thus, while conceptually n is two strokes, like r, it actually can be written with a single stroke -- and in many cases it obviously was, as it has a round bottom instead of the expected sharp corner.

In my view, those cases where the plume of r or s seem to have been drawn from the top down are cases of late retracing.  Retracing in the wrong direction makes those plumes thicker in the wrong places and "uglier" than original ones.  (That is why in the Chinese and Japanese scripts the order and direction of the strokes is part of the definition of each character.)  Indeed I consider those malformed plumes an important indicator of retracing.

All the best, --jorge