From what I understand about practices such as Reiki, even if they work as people claim they do, and as your wife has apparently witnessed, it doesn’t mean tha it is spiritually good. From what I have read, it us a manipulation of spiritual energy. The danger lies in the fact that it is an attempt to manipulate the spiritual world without God. Similar in nature to using a medium to communitcate with the spiritual world, rather than depending on God’s Will. Similar to Eve seeking knowlege without following God’s will, she wanted to do it on her own. I believe there are Mediums and psychics, I believe that an Ouija board works, for instance.
If a practice heals the body, what good is it if it hurts the soul, if it takes us further away from God by trying to manipulate teh physical or spiritual world outside His Will.
So the discernment should be not whether it works, but “does it take me further away or closer in my relationship with God.” I can’t really answer that for anyone else, but I don’t want to eat the apple.