Player fouled out...

[Idaho]

Okay, here's the sitch.

B2 fouls A1 during a try for goal. The basket goes in.

A1 shoots the free throw, which misses. As the ball is coming off the rim and players are scrambling for it, but before either team has gained control, the table sounds the horn. Trail sounds his whistle and both officials go to the table to see what the deal is.

Table informs the officials that B2, who is still in the game, has 5 fouls. Officials replace B2 and re-administer the foul shot, which goes in.

I know there are probably multiple things wrong with this situation, just wanted to get your feedback on how it should have been handled.

My initial understanding is that, first of all, the bench shouldn't have sounded the horn while the ball was in play, no less not under the control of either team. Also, similarly the trail shouldn't have acknowledged the horn for the same reason.

But, since the whistle was sounded, they should have gone to the AP arrow instead of shooting the free throw again, since it was already completed.

Am I close?