How do you mean? Are you saying they won't fit, or is it due to switch spacing etc? I've made the area where the PCB goes quite a lot larger than the phantom, filco pcbs. I've measured my KMAC PCB and it will fit with the exception of the USB connector which, as I've said before, I'll have to cut off.
EDIT : I've measured the switch spacing on my KMAC PCB - it's the exact same as my plates. I've measured the dimensions of the KMAC PCB that I have - it will definitely fit inside the case.
The plate you prototyped is based off the original file I sent you. I designed that plate for Phantom PCB to fit inside Filco/CM case. They do not fit KMAC or any other Korean PCBs.
You're right that switch spacing is the same... it has to be because all keyboards use standard spacing of 19.05mm between each 1x key size. However, look closely at the empty spacing between the function row and the number row. Spacing is different between Korean designed PCBs and Filco/CM/Phantom, or any other mass produced keyboards.
KMAC PCB might "fit" inside this case, but that's because it's smaller than Filco/Phantom PCB. Not only will it be loose, you'll need a different plate for it.