There are probably quite a few cars out there with COD's that maybe should never had got them. Of course; you try to limit the mistakes.
However the car you refer to (and I think Carlo was in on the discussion at the time) had an owner that provided written material such as magazine articles to show that in 1982 the Mark 2 Escort was tested with the engine that ended up in the Sierra Cosworth. Therefore a period modification. If you have a problem with that; and I know you have asked me and I have explained this in the past; please take it up with the Rally Commission Chairman