I should've put in the SUSPIT and SUSYAW channels in the previous screenshot. I re-aligned ETMX till I could see IR flashes in the arm, and also was able to lock the green beam on a TEM00 mode with reasonable transmission. As I suspected, this brought the Oplev spot back near the center of it's QPD. But the answer to the question "How much did I move the ETM by" still varies by ~1 order of magnitude, depending on if you believe the OSEM SUSPIT and SUSYAW signals, or the Oplev error signals - I don't know which, if any, of these, are calibrated.