I gave reasons why investigators may not always confront witnesses. My opinion is as valid as your opinion that they trot back and forth every time they want clarification of a point. No wonder they needed such a lot of staff if that's how they work lol.
The statements made to the first investigation are there for all to see and read. The idea that a different translator can 'correct' them is crackers imo. OG can ask the witness anything they like but four years after the event it's unlikely that anything new or useful can be remembered.
In this way, at about 21.05 the witness came to the Club, entered the room using his respective key, the door being locked...At about 22.00 it was his wife Kate who went to check on the children. She entered the apartment by the door using the key...
http://www.mccannpjfiles.co.uk/PJ/GERRY-MCCANN.htm
Despite what he said in his previous statements, he states now and with certainty, that he left with KATE by the rear door which he consequently closed but did not lock given that that is only possible from the inside. Referring to the front door, while he is certain that it was closed it is unlikely that it was locked as [because] they had left by the rear door.....
He followed the normal route up to the rear door, which being open he only had to move [slide] it, that being the way in which he entered [was entering] the lounge,
http://www.mccannpjfiles.co.uk/PJ/GERRY-MCCANN-10MAY.htm
But it still doesn't give the reason WHY he changed his statement. IYO he had been forgetful over which door he used - IMO he was correcting a misunderstanding which occurred during his first interview over which door he was referring to. This was due to the fact that some people referred to the patio doors as the Front Door and the carpark facing door as the Back door and some people did the opposite.
IIRC You don't take into account the state of mind Gerry would be in during that first interview, or the language barrier, - or that it was the first interview for everyone and the PJ officer was not familiar with the layout of 5A. I do.
Anyway this has all been discussed before at great length G. However I don't see SY discussing it in the same way as we have - when they could get the answers from the man himself - and could seek corroboration of those answers with their Oporto counterparts. As I've already said - SY could have compiled a list of queries which may have emanated from the non verbatim summarised statements - and then interviewed the witnesses themselves to gain clarification in one interview.
Of course it is also a possibility that SY already had the 'clarification' to hand - from amongst the 40,000 docs in their possession. Info. which we have never seen because it wasn't released to the public.
AIMHO
ps. I referred to the translator - because he/she was one of the people who was present at the first interview - and IMO would remember it simply because it WAS their first job to do with this horrendous case. The translator at the 2nd interview would be aware of the reason Gerry gave for changing his statement - even though that reason was not included in the summarised statement.