To my knowledge, PCB stabs have bent wires and those do not work with a plate, because of the rubbing.
Plate mount stabs should come with straight wire and work fine with a plate.
I guess Cherry meant the PCB stabs to be used only with PCB-mount switches. Sth like "If you have a plate use plate-mount stabs".
You can easily bend your own stab wire from 1,5mm - 1,6mm stiff wire (piano wire) 100mm wide CtC, length of legs ~12mm IIRC.