As the yokes are mechanically linked, I am not too sure how such information is registered on QAR FDR or is it mainly according to the pilots accounts ... ?
Yes, the yokes are mechanically linked, but there is a "break out" mechanism on the torque tube between them, so it is possible to force the yokes in opposite directions. There are pitch transducers on the bottom of each yoke, so the DFDR will pick up the position of each yoke.