[toni-a]

Before assuming it's a stupid post, focus peaking does work on manual focus lenses yes, however, for native Sony lenses, even if you are on manual focus when you rotate focus ring the camera automatically switches to focus peaking with non electronic lenses you have to press focus peaking button yourself.
As for the adapter, since it's a canon-canon, it's only job is to transmit electronic signals and increase flange distance so it's construction is the same as an extension tube, although it will not act like an extension tube