Hollow legs?
Also that seems fairly unusual to have extra spaces already there on both PCB and the plate.
It's pretty common.
Many keyboards will support multiple layouts on the PCB (usually ansi, iso, and japanese for modern ones), and it's not too uncommon to see multiple layout support on the plate as well. Most of my hall effect keyboards immediately spring to mind. This is a well-thought-out design, and I am sot surprised to see such things. Were I making a keyboard design like this, I would include extra switches where possible. I mean, the same thing happened with the phantom.
Edit: I checked the legs: they are actually quite thick.