skwinty,
Unfortunately that link to altimeters does not apply to the case in question as it does not cover barometers inside planes. That is where the errors of interest arise. They arise due to the difficulty the plane designers have in providing the instrument with true outside air pressure. The best they can do is experiment to find the best place for the static source. The problem is that the best place varies with speed. The calibration chart would reveal the speed beyond which they did not measure the errors.
Basil,
As there is no sign of steps in the data at the transition level of all 11 prior flights, it appears that the recording ignored the pilot's adjustment of the reference pressure. However the ADC may well have made adjustments relating to airspeed, but any such adjustment would fail at speeds for which the errors had not been measured.