As Harrison is or was a visiting professor in his subject I doubt anyone on here has a superior knowledge and understanding of his particular field.
Mr (professor?) Harrison appears to have said many things but I believe these to be relevant.
“The use of a specialist EVRD and CSI dog could potentially indicate on whether Madeleine’s blood is in the property or the scent of a dead body is present. In relation to the dead body scent if such a scent is indicated by the EVRD and no body is located it may suggest that a body has been in the property but has been removed”. He later in the same document qualifies this to say it is “intelligence rather than evidence”. So we have a sort of dichotomy: intelligence v evidence.
He also says:
“This report has highlighted the extensive and professional efforts made by the Portuguese authorities regarding the search to locate Madeleine McCann alive”.
The part I underline is perplexing, I do agree.
I can't think Harrison didn't know that we don't send (and never have sent) dogs to America to be trained on human remains.
There are at least two (separate) FOI answers that confirm Eddie was no exception to the general rule.
It is clear from Harrison's reports that he simply quit trying to sustain an untruth he realised was unsustainable.
On your other point, yes, Harrison seems to have been (genuinely) impressed with the efforts of the GNR dog-handlers to try to find Madeleine, and I am very happy to respect Harrison's professional judgement on that one.