Thanks for the help. To clarify after taking a closer look (attached another picture from the rear/right bolt):
The play/movement: To be more precise, the metal threaded inserts are solid and fixed—they don't move inside the frame. The 'play' I’m experiencing is actually the caliper tilting because the mounting surface isn't flat.
The right/rear mount: As seen in the photo, the caliper is not resting on paint at the rear mounting point. It seems to be bare material.
The threads: The threads themselves appear to be perfectly straight.
The left/front mount: That ragged paint edge might have been out of the box or caused by the caliper tilting while trying to align it.
In your situation, and having an LBS that I trust completely, I'd take it to them and get their opinion on whether or not facing the mounts will solve the problem, or whether mounts are simply installed incorrectly.
When I buy a frame, I'm prepared to have brake mounting surfaces, headset bearing cups, and bottom bracket shells cleaned up by my LBS. It's nice when I don't have to, but I don't take it for granted that these will be perfect. I'm prepared to pay for that eventuality.
If the mounts aren't installed properly and therefore the calipers can't be installed and centered normally, that's a manufacturing defect and a different story. If that was the case, and a professional mechanic can't sort it, then I'd be asking LC to replace the frame.