I see some confusion here.
Orchiectomy is surgical removal of the testicles. That is a permanent action which can not be reversed.
What we would call Chemical castration is accomplished through drugs. That is the process we would normally call Hormone Therapy. With that, drugs are used to drive down testosterone to a near-zero level, without surgical intervention.
I'm not sure which of the two he has done from your posts.
After Radiation Therapy, it is possible that his PSA would rise, then begin to fall in the months following the treatments. The range you mention does seem unusual, but I'm not the doctor.
Not everyone reacts to the many drugs that can be used in Hormone Therapy the same way, and what works well for one may not work at all for another. You will need to work with an expert oncologist to find a workable treatment plan.