Thinking about anomalous gallows...

[ReneZ]

I am also uncertain if the variations in the d-shape are meaningful.

GC recognises three main types of d, which he transliterates as 8,7 and 6. In addition, most alphabets recognise j as a separate character.
The frequency of occurrence of these three types is:
8:  10,346 times
7:    2715 times
6:      115 times

In comparison, m occurs around 1050 times (GC and ZL transliterations) and g around 160 times