i dont use cpp any more because of that lousy customer service.
the 3 things that could cause your problem are the housing end not being square, and youve checked that.
the caliper brackets not being square. i looked at their site and it looks like the brackets have a step built into them. that would be very suspect as to being the cause. the step needs to be perfect to keep the caliper square.
the calipers. i find i hard to believe they would be bad. it could be possible that the cheap over seas reproduction stuff cpp uses could not be made perfectly square, but i would be most suspect of the housing to caliper brackets.

i would take the wheel and caliper off. i would put 2 nuts on wheel studs to hold the rotor firmly and squarely on the axle. then i would figure some way to measure the angle of the caliper bracket to the rotor. if they are perfectly parallel then your down to it just being the caliper. if they aren't parallel you have found the problem.