Yes but, it doesn't "need" to be flat, again, since this is by design. You won't be able to mix and match with SA anyway, since the MT3 keycaps have also different texture, different concavity and so on (PBT instead of ABS). The idea, if I got it well, is to emulate old keyboard curved surface on todays flat keyboard's surface, keeping in mind that the keyboard will also be placed at a small angle (so the R3 will be "flat" in that it will be parallel to the ground surface when the keyboard is raised).
Now, if you have compelling reasons to have the profile altered, you could try to convince Matt3o in
his thread