excuse me but it is quite normal for a replacement ball to be used once the original one has gone into the crowd to keep the game moving along instead of the linesman stood looking in the crowd for it, asking can we have our ball back please
the problem occured when the original ball came back on the pitch BEFORE the replacement was used "it does not allways" because that one was that ball that was in play and not the replacement one.
However if the replacement had been used in game play before the original ball came back then it would have been deemed as the game ball and the try legitimate
this should have been spotted by the referee.and the replacement taken off immediatly when the original ball returned.
the welsh side did nothing wrong playing the ball they were given to play with. it is all down to the ref'and the linesman and the misstake they made.not seeing the error.
the shame therefore belongs to the REF and not the welsh team.