correctable error situation
 

4-20-3 says the free throw ends when it is certain the try will not be successful. Does that pertain to an "air-ball" or also when the try bounces up and well off to the side of the rim? I'm wondering about this in a situation where Team A is erroneously awarded a 1-1. A2 makes the first and the second bounces well off the rim. While going for the rebound A5 displaces B5 before the ball is touched. The officials are then notified of the error. Is A5's foul charged or nullified?

I vote for "charge it".

2-10-4 applies... foul is canceled.

Agreed, you are still within the statue of limitations for a dead-ball correctable error. Wipe the free throw and give A the ball OOB.

You have to judge whether it happened before the free throw was over, and this "during" the free throws.

Right -- and that's the OP's question.

IMO, "bounces well off to the side" means the FT is over, and we should enforce / charge the foul.