Was is preterit. Gone! Clean cut. Has been is past "participle", of participate? That is, the emotion of the past act carries into the present, drags into the present as it is remembered and talked about.
It's the difference between past and present. She is being supportive. This is an action in the present that is on-going. She was being supportive. This is an action that happened in the past, and that concluded in the past.
The only difference between a cerebrotomy and a encephalotomy is the part of the brain that is being cut into. In a cerebrotomy the brain substance is cut and in a encephalotomy the actual brain is being cut open or removed.