So, there are actually more ZYNSWITCH action types, including the one for "R"elease. And triggering "P"ush and "R"elease consequently does really treat all the timing and trigger the corresponding Short/Bold/Long actions. (So, the other implementation of timing in zynthian_gui_base.py is probably completely unnecessary.) So, it looks like it really works!
Now back to the visual side. The Audiowide font does not seem to include any useful unicode symbols according to my computer’s font inspector. Surprisingly, it actually displays at least the unicode “STOP” symbol on the zynthian screen. But nothing else.
To be continued…