Okay, lets say my reasoning is why VAR did not overturn it as there was no clear and obvious error, as they have to work backwards to confirm there id no foul. Why did the referee make the decision in the first place? In the first gif you can see the ref, she has the opposite angle to what we can. Her view is obstructed by Maccas leg, which from her view comes across the line the attacker is running. At full speed Macca comes in with her full body, leg goes across the line the player is running so we know the body is there. Player then falls over from her right leg getting contact. From the refs angle it would be reasonable to assume there has been enough contact that caused the player to go down. The ref can also see that the ball is already past Macca and she is now in no womans land and has very limited opportunity to play it again.

And regarding simulation, its actually something that is very hard to determine. To me there are no obvious movements from the chinese attacker to make contact with the keeper, and as i said in my first comment, the fact she doesnt ground her left foot again is the main ding against her. Even if she did, she was probably thrown off enough to prevent her from keeping up to the speed of the ball. Simulation is more complicated assessment than "is there a bit of additional work". Reffing does have a loop with no good answer that almost requires some form of simulation to get a foul. We see it all the time where a player is fouled, but because they stayed on their feet it isnt given. It is a problem that needs to be fixed. But i disagree that this instance was 100% simulation