If you're not 100% sure the whole of the ball has crossed the line, you don't give the goal.So going back to the OP, where there is the element of doubt, do you give a goal or not?
I'm going with 'no goal'.
It's why I very rarely give a throw in when the ball is on the sideline and I'm AR, I just shout 'play on, stayed in' etc, because majority of the time the whole ball hasn't crossed the line though the players always seem to think it has for some bizarre reason.