If even discovery of a body doesn't increase the credibility of the alerts, I fail to see the point of all the effort being put into discrediting the dog alerts over the years.
I'm not sure what Grime and Harrison were expecting as corroborating evidence but one thing is certain, if she did turn up alive it can't have been madeleine's cadaver the dogs were alerting to.
If her remains were found within a couple of kilometres of the apartment would that corroborate the alerts?
Maybe there is still the possibility of her wandering and then being hurt then picked up then killed. So the body is still not linked with a dead Madeleine being in the apartment.
I find it tricky from all angles. Maybe a confession is the only fool proof corroboration.
But a confession can only come from the guilty parties, so if they are innocent where is the confession going to come from. Is there someone else who could confess?