But if they heard something they could stand and look.
I think we are looking the wrong way, it didn't need to be the Moyes who saw the mystery couple IMO, it is obviously something released by the investigation. A confession they have but they haven't released to us via the PJ file IMO.
Their balcony is set back both from the road and the rear of the building. The roof of 5A sticks out further as well.
Even if the Moyes stood, they couldn't see anyone passing the side of 5A, nor across 5A gate, nor up the steps.
Because of X
6AX 5A hedge obstructing their view, neither could they see anyone, including Jane T, who passed up that road on the westerly pavement unless, maybe, if the person was walking very near the kerb.
Maybe, maybe not, they could see Gerry and Jez talking on the edge of the Westerly pavement/in the gutter ... if they looked at the correct time.
If they looked at the right time, then they could see Jez before he crossed the road to chat with Gerry
The chances of either of the last things are quite remote.
To be quite frank, imo, they didn't see anyone from the Tapas group. They couldn't, their line of vision being blocked even standing up