Looking at the text on F66r and F106r, it seems as though the gallows characters were written as short vertical stokes (like a lowercase 'i' or a short 'l') first, and the upper halves added later. In some cases there is a kink in the vertical stroke, sometimes a break, sometimes some overlap, sometimes a marked change in ink darkness. I've noticed this in many places in the MS, but these two pages are quite clear in the images I have, and contain lots of examples so that I'm pretty sure the effect is not imaginary.
Since the script in general seems to flow rather neatly, it seems a bit odd to me that the author would choose to write these characters in such an interrupted way when they could be done without lifting the pen from the page. Could it be that originally the gallows characters were written as short vertical strokes only, and the tops were added at a later time? If so, why?
If the 'alphabet' is an invented one then a possible explanation could be that the gallows were added to draw attention away from characters that looked too familiar and might aid in deciphering the MS. I wonder how the script, or a modified transcript, would look if the tops were taken off the gallows characters. Something to try one of these days!
Jon.