If Gerry's check was after his talk with Jez ( Jez wasn't certain whether Gerry was coming or going from the apartment) then that would explain Gerry's 'normal' behaviour. After that visit there are no witness statements that say anything about how the McCanns and their friends were acting. In fact I can't remember any of the serving staff actually mentioning the seeing Kate run back to the table and raise the alarm.
As to the traffic issue Gerry himself says that he didn't see anyone on the previous nights while checking so I think he would have a good idea how likely it would be that he would be seen.As to his friends letting him take a particular course of action you are assuming they knew what had happened at that point
Gerry didn't go into Pdl he just took the one road back to the apartment. He could have no idea what was going on elsewhere in the village.
I find it hard to believe that when they parted company Jez would not notice which direction Gerry headed off in. i.e. Up to road to the apartment, or down the road to the restaurant. He didn't just vanish into thin air on the spot.
If you really believe that all those people could take the news that Madeleine was dead, and still remain sitting at the table eating their meals and carrying on as if Gerry had just told them he'd found a dead beetle on his way back to the table, then we have no chance of agreeing on anything Faith.
The shock would be massive! It is not humanly possible for them to be able to appear totally unmoved - and to calmly start planning a cover up. Kate would have been beside herself from the moment she heard the news. This was her little daughter FGS! There would be pandemonium! And no way would the restaurant staff have NOT noticed it. However, they didn't notice anything odd, and that's because nothing odd happened.
Give it up Faith - the reaction and behaviour you are suggesting is not humanly possibly to achieve - especially when you have had no notice at all of what is about to happen.