How good is your pareidolia?

[oshfdk]

When writing a Ch,  for example, he would write an e and then an h with the tip of the ligature precisely touching the tip of the e.  Ditto when writing s, t, etc. And the original figure outlines are generally ~0.2 mm wide, independently of direction.

It's interesting that you chose ch as the example, because it seems to prove my point. There is a whole solution theory on this forum that works by treating various ways of misaligning ch as different characters, because ch's are often misaligned and in many possible ways (above/below/overlap or gap).

Also, when connecting lines with a quill, as long as the ink is still wet, you will get natural smoothing of the outline at the point where two ink blobs touch one another.  I don't think it takes more than normal human ~0.25mm precision to write a proper ch, but the scribe managed to fail even this in a large number of cases.
Looking at the retouch jobs the smoothing doesn't seem to happen when the old ink was already dry.