It is firstly obvious to me that the aircraft was completely outside of its normal flight envelope. The aircraft was deliberately flown into the building with no regard to normal flight procedures.
That cannot be disputed.
The factors that could have influenced the pressure altitude are numerous. The only thing I can say with confidence is that the error in question would be the sum of all total instrument errors.
I would not be able to isolate a single variable with great statistical certainty.
Even if you extrapolate from the original data, your next problem would be the low sample number and lack of repeatability.