I don't follow the information.
Was the tree unpotted then planted in the soil or was the whole pot with tree in it buried in soil?
Why would roots be attached to the bottom half of the pot? Roots grow in soil or potting soil. Roots don't usually attach to the pot in my experience.
What is the bit about missing wiring? Do you mean you can't see any wires left on the tree that might be strangling the branches?
7 months in the ground is not much for a juniper. I need to know much more about where it was buried, why and what soil it was in and how long it was buried for.
Weak on one side can be number of things:
The first, and probably most common, is light. Sunlight comes from one direction as the sun passes through the sky. In Southern hemisphere the north side gets most sun and the south side of a tree is shaded most of the day. In northern hemisphere the sun travels across the southern part of the sky so north side of trees are often in shade.
No mention of where you live but you can see that can be critical info when trying to solve bonsai problems or when giving advice on what to do when. Please add a location to your profile so we have a better understanding of your seasons and local weather.
Lack of light usually affects an entire side of a tree. See if you can remember which way the tree was when it was buried. Was the weaker side away from the sun path? Was the weaker side close to a fence or wall?
Another factor making parts of a tree weak is root problems. We need to know more about how the tree was buried and how it was dug up. Did you cut roots when you dug it? Did you put it into this pot after you dug it up? What potting soil is in the pot? How long since you dug it? Where has it been kept since digging and what care has it had - watering, sunlight, fertiliser, temperatures, etc.
Since certain roots are often linked to supply certain branches root problems often show up as a single branch or several nearby branches deteriorating. Please check to see if the problem is confined to a single or a couple of close by branches.
Physical damage to branches can also affect parts of a tree. Any chance some of the weakening branches may have been damaged during transplant or before or since?
One of the problems with junipers is that they are very slow to show there's a problem. By the time the branches start to go yellow we've forgotten what happened a month ago.
Again, please check to see if the affected part is on one or a couple of branches.
