Airliner Training - Take-off - Cannot get to A-rating

Just for fun I am trying to get all trainings to at least A-rating.
For the Airliners Take-off training I cannot get it to that level.
Normally YouTube is my friend to show some tips/tricks, but it does not help this time.

When I use FLX/MCT the aircraft builds speed like a rocket. High pitch does not help as when I engage the auto pilot as requested, nose drops and speed is out of control again.
I have tried to set FLX/MCT to tick the box and then set it to CL already. Plane behaves better, but my grades don’t.

Any help welcome.

Maybe the Airliners Take-off training is broken, like some other training flights.

Yes, that could be, just like the ones for the Cessna 152, where you need to set the mixture to full rich yourself to be able to climb fast enough to reach the target altitude.

Things like this then help to still obtain an A-rating.
So, who knows what trick to use to get to that A-rating for the Airliner Take-off training?

At what time/altitude do you engage the AP?
Did you reduce the throttle to the CL (climb) position when at the acceleration altitude after your initial climbout?
FLX/MCT is only your takeoff throttle setting, and the autothrottle will not work unless in CL.

At the time the instructor tells me to do that, but I have also tried variations, e.g. switch to CL sooner hoping speed control would be better (did not help).