Sux! I just witnessed the same:
My son had a hard match. Semi final cup. He lost the first leg 2-0. Second leg he "won" 3-0. Main screen says " no mister, it was 3-1"
Never saw his opponents goal.
So he is out of cup.
If this happens to me I quit the game. This is no fun playing if u must go to the main screen en check if u really won.