There are two 3-4ft roosts and since they were first released into their forever coop some have always slept on top of the nesting boxes, so there's that space too. I find there to be plenty of space for 12 hens to sleep in there at night.
You need more roost space, for one. Sure, they can try to squeeze in, but seems that some of them don't want to or aren't allowed to, and now would rather go elsewhere to sleep. 12 hens should have roughly 12' available, to allow them to freely get up and down, and I would not count/encourage them to sleep on top of nest boxes as that leads to soiled nests.
In your 4th photo with the roosts... is that photo oriented correctly with the chicken wire overhead? The bars there are awfully close to the wall if that's the case. Is there at least 12" between the bar and the wall? Birds may not want to use roosts that cause their faces or tails to be smashed against a wall.