yanrair, In QF32 they had more than an extra pilot. Given the type of flight and the training happening I expect there was a bit of adrenaline floating around the cockpit the heightened initial reaction. The comment before take-off indicates this, it was never going to be an everyday flight for the PIC or the pilot checking the PIC. They did a great job and were very lucky also.
I simply do not believe the jump seat pilot on the first Lion Air MCAS event flight picked up a "runaway trim" there certainly has not been any evidence of that been made public. What has been reported has been the entry in the Tech Log. This entry was alone the line of "STS running in wrong direction/reverse".
This to me means that all three pilots were not surprised to have the trim activate, in fact they expected it - just it was working opposite to what they expected.
If they thought they had a runway trim would you not expect a Tech Log entry to be something like - Runaway nose down trim (intermittently).