I have always wondered this as I have a severely scratched Jupiter 8 lens and that thing is like shooting through a mist filter. Everything glows, no matter the aperture. I have read from people who have done similar things successfully, or so they claim, and also advice against it because it can alter the optical characteristics (which does make sense too).
My advice would be to test the lens as it is, see how much actual impact it has since its very lens dependant and use a lens hood too, and if you dont get the results you like just sell it on. I wouldn't bother trying to botch a homemade repair with a Rolleiflex personally, the risk is too high.