I would suggest this was one of the diligences carried out by Operation Grange and\or the Polícia Judiciária prior to the case being reopened independently of each other ... so it is a base which has probably been covered.
Yes it is possible that they may have asked the witness already, I don't know. IMO it is possible that police were so concentrated on the charity collection in this statement, that they may have completely overlooked the mention of an open manhole?
BTW is there a statistical tendency in some wandering cases to walk downhill?
Going downhill begins by going south along Rua Martins. Just before the supermarket there is a choice, either continue south along Rua Martins, or fork right onto a path towards supermarket car park, and both choices appear IMO to be equally downhill.
The first choice (stay on R Martins), when continued by always choosing the most downhill option, passes through junction B.
The second choice (fork right to supermarket car park), when continued by always choosing the most downhill option, leads along a path around the west side of the supermarket building, and then passes through junction A.