Just thought of this...the forced isekai to JP people gave them a skill and then fixed what it was seen as bad status, the clarovayance guy got his youth back for that, at least this is the theory they came up with and never gone over that(in the manga).
But then...why is Doc guy still wearing glasses? His sight should have been restored, damn, his skill should heal it if that doesn't.
I know, I know, is because he is the glasses guy and 90% of his persona is in the frame, still pretty dumb.