It seems improbable doesn't it but from the very beginning Silvia Batista started undermining Jane's sighting that is when the problem started. I propose that Jane saw something that she wasn't supposed to see and the various factions and players have had their reasons to discredit her.
Was Silvia ever the interpreter in any of Jane's statements. How impartial were the interpreters that were otherwise used? We will never know.
I was looking for the post about Gerry needing Jane for his alibi. I have subsequently been thinking getting rid of Jane's sighting could be for Jez' benefit too for he does his best to change the meaning of what Jane saw too.
Jane's sighting once she had admitted it can't easily be retracted for she immediately spoke about it to Rachel, then to Fiona, Russell must have told at some time too, then to Gerry then to Silvia and the PJ in the early hours of the morning 4th May.
She doesn't know that it is going to bring everyone down. But if my hunch is right everyone would have preferred Jane not to have seen Tannerman. If she hadn't seen Tannerman they would be only too happy to have seen Jane go marching by in her flip flops with her perfect timing giving Jez and Gerry the alibi.
Finally everyone is happy as Tannerman has been converted to Crecheman the whole lot can breathe easy again.
Too bad about him going the wrong way! Too bad about him being unnamed. Too bad that the child he was carrying was conscious. Too bad the pyjamas were not the colour Jane saw. Too bad that Crecheman didn't use the blanket he was carrying.
You say Silvia 'undermined Jane's sighting' which suggests intent. You are ignoring the possibility that Silvia had a good reason for being confused by Jane's sighting - that it didn't make sense.
At some point she translated the statement of one of the ladies who belonged to the group and that she describes as a brunette one. This lady said to the GNR elements, and she (the witness) translated, that she had seen a man on the road who might have carried a child.
This situation surprised her because she (the witness) was convinced that when the lady saw the man, the lady was in a place from where she had no angle of vision for the place where she saw the man. She doesn't know exactly what was the position of the lady when she saw the man, but she knows that the lady said she saw the man in the street in front of the Madeleine's bedroom window, walking in the direction of the street that then leads to the Baptista supermarket.
http://www.mccannpjfiles.co.uk/PJ/SILVIA_BATISTA.htmIf Jane told the GNR that she saw the man when she was walking up R Dr F G M she wouldn't have been able to see the man if he was in front of Madeleine's bedroom window. She would have seen him only when he reached the junction, as she said later in her statements.