Good point. I didn't think about this, that it might be necessary to obtain a final result from ECHR, in order to vacate the calunnia conviction in Italy.
But my understanding was that ECHR deals with the Italian government, not the judiciary. Italy could make an friendly offer to settle without fighting, and my understanding is ECHR encourages that result to avoid drawn out legal battles and the expense of legal costs and court time. I'm not sure what the exact mechanism is for a friendly settlement, but it doesn't mean much if they can't annul the convictions of a flawed trial.
Also, IIUC, ECHR cannot change the calunnia conviction, only find against Italy in violating Knox's rights in achieving the conviction. The result of 'restituto integrum'(?), I thought meant re-opening the process for a new trial. However, since the statement itself is the crime, if the statement gets tossed, its an obvious non-case.
I'm not a lawyer and don't know the specifics on this. I think Numbers is our best chance of sorting it out.