I agree.
Anyway - if it was all an invention - for whatever reason - then surely they would both be word perfect. ''Why didn't you come when Sean and I cried last night'' is hardly difficult to memorise.
IMO it's mistake to put too much reliance on summarised, twice translated statements being totally accurate. None of the summarised statements we have to go on have been signed by anyone to say that they are accurate translations of the previous translations. It only takes one wrongly translated word to change the whole meaning of a sentence.
IMO
In my opinion you should also be word perfect if your daughter said something before disappearing. You would not mix up 'me and S**an' or "S**n and I" with "the twins". Neither would an interpreter.
The McCanns said this incident was possibly significant because it could have been due to an abductor being in the apartment on Wednesday evening. At the same time they have played down the more obvious point; their children cried and they still left them alone to do it again. They don't seem very empathetic, do they?