One bit I have been musing about is the time of the accident, 0540 in the morning after they already had done a night flight from Moscow. Not the best for fatigue.
Karel, if anything is not set as required on the TU before take off, it will give you a config warning and the take off light won't go out. I'd be very surprised if the stab had not been set as required, of course if that was true, then we'd have a major suspect.
CG is regulated via fuel in the TU, so it should not have been a problem, but of course, who knows.