Sorry, I don't have any idea how they test nor what parameters constitute "passed". Your description is clear that insufficient voltage is being generated at idle and low RPM, that can only mean a couple things, loose belts not turning the alternator fast enough or some malfunction with the voltage regulation system. You've R&R'd the alternator so I'm assuming you tensioned the drive belts correctly when you reinstalled it, you made no mention of checking it so that leaves the voltage regulator as the next logical step.

It's held in by a couple screws to the rear side of the alternator, with a stubby screwdriver it can usually be pulled and checked fairly easily and quickly.

Engine ground is on the Driver's side, a bare woven copper braid between the bell housing and the chassis.