In the calibration window we have 8 points in addition to the center, at which we can apparently set offsets. But the User Manual only tells us to set the height in the center, and says nothing about the other points. Do these 8 outer offsets actually work, or are they non-functional?
They do. You can use the same procedure as the center point to get the nozzle height at each of those. Then pick the lowest of all 9 and treat that as your zero point. As in, if position 7 starts touching your calibration paper at 181.5 and let's say all the others touch at 181.2, then you would set your nozzle height to 181 (181.5 - 0.5) and position 7 should show 0.00. The other 8 points would be set to 0.30 since they calibrated to be 0.3 higher that position 7.