Yes as a former elder if someone confessed to wrongdoing the first thing you were instructed to do was to let the po know because he may be aware of other instances then the elders gathered at the end of a meeting and then rest of elders would be made aware that bro/sis done this or that , then when 3 elders meet with the person then the body of elders would be made aware of that also.
So yes no real confidential