Exercise No3 - Answer

Though it doesn't say so L47D deals with cards played in rotation. Declarer is not allowed to withdraw the §4. If the TD is convinced that east caused this irregularity by purpose a well deserved penalty (adjusted score) at least compensating the gain should be east's share (L72B1).

Remark:
There is a feeling that declarer should be allowed to change his played card from dummy being played after his RHO had played a card which is replaced because of a revoke. The laws don't seem to allow this. Of course if the feeling is that RHO by purpose revoked out of turn a severe penalty may be given.