If previous character and behaviour of a suspect was of no relevance in a police investigation why do police investigate it in the first place?
What police investigate and what I can lay my hands on are two different things completely.
I can assemble a minor amount of independent evidence that Madeleine was not maltreated in the past, albeit questions remain.
We have a bit more evidence about how Madeleine was treated during the holiday. Overall, I would assess that as not great, whilst I accept the archiving report says they could not be prosecuted for neglect.
Their behaviour after the event I would characterise as extremely odd. However, I do not know what normal behaviour would be if the McCanns are entirely blameless, nor can I characterise their behaviour if they are guilty of a serious crime. I am not a criminal psychologist.
Perhaps the police have capabilities in character analysis and behavioural analysis. I know that I do not.