Hi Max:
For connecting the two halves, actually 3 cables are required: VCC, Grnd
and Serial (please correct me when I wrong, but I am assuming standard
QMK configuration). In fact, any three cables should do, if you are not
afraid of messing around with the plugs. I e.g. use RJ9 for connecting
halves of a manuform split keyboard (I am in Mexico, and telephone
cables are much easier to get and cheaper than TRRS).
The keycaps should not stick out. Have you tried to push it in
properly?
Best regards,
Robert
Excerpts from mm jj's message of 2021-02-08 23:04:03 -0800: