If you have isolate the hen that is the bully hen what you are seeing is most likely the rearranging of the pecking order. When you take out the instigator, the other girls that are in the coop and pen then have to find their new place in the order. A pecking order is the staple of the chicken hierarchy, its how they know who is above who and who is below whom.
When any member is removed from the flock whether it be for illness, death, or in your case chicken jail, the order must then change. This is what we want to happen, so when you reintroduce your hen that is in jail she will have to start at the bottom thus removing her from her alpha status. Some other hen will battle for that position and your bad girl will have to reclaim that spot thus curbing her aggressive bullying behavior. The pecking order can be look quite nasty, but as long as no one is drawing blood or literally pulling feathers out they will be fine.
What you are witnessing is normal, the rest of the gang just has to get their ducks in a row. It my take a few days for them to settle on an order. But once they settle down keep your bully hen in chicken jail for a bit longer. We want to make sure that when you put her back she does not just pick up where she left off. The order needs to change so that when she is put back with the flock she is the new kid on the block and no longer holding the alpha hen position. You are purposely disrupting the pecking order for this exact reason. don't sweat it, if they have plenty of food, water, and space they will be fine. Yeah, its not uncommon for hens to mount each other when competing for a position, its what they do.
I have a pair of hens that always seem to be competing for a specific spot in the pecking order. They will mount each other, chase each other and so forth. As long as it does not get too aggressive I just let them battle it out. They have been fine for the most part, once in a while I have to play referee. But they work it out in the end.