It's very sad to see birds chained like this, they get zero mental and physical stimulation. The area also doesn't look very clean, it can easily become a breeding grounds for all sorts of harmful germs. One of my biggest concerns are that one day, a wild animal may break in(since the aviary floor is dirt), and the birds will have to suffer because they can't escape from being chained.
If you are unable to give better care, you should rehome the birds to someone who is able to. I know you said you are trying to do better, and I'm glad, but honestly, the birds shouldn't stay in this condition for much longer. As stated by other members, you can easily transform the aviary into something that's much better for them.