Retread are only as good as the casing that is being retreaded. Treadwright is a pretty good retreader and have good inspection standards for their casing. They also have a good, modern facility in Edgemont, SD. I have been to their facility and was impressed (my Dad used to be in the retread game in MN). I have run their retreads on daily drivers and off-road trucks without issue. I even drove my old XJ from Rapid City, SD to Moab, wheeled 10 days, and drove back all without issue (from the tires atleast).
Bulges in the tread face like the picture above are the result of poor casing inspection or preperation. Casings with patches or punctures should NEVER be retreaded (I imagine this casing had a puncture that was not noted). Also, when they retread a casing, they actually grind the old tread off. Grinding creates heat that can cause the casing to expand. This expansion will cause the casing to be overground to the point it will fail when capped.
Treadwright will retread your casing and ensure they are returned to you. I would suggest if you have good core tires, have them retread those. Then you know what you are getting back for a carcass.