Could the crowds at the temple see someone standing on the pinnacle?
Yes, the crowds at the temple could see someone standing on the pinnacle. The pinnacle was not as high as modern skyscrapers, so it was no problem for the temple crowds below to see someone up there; it was easily within eyesight.
Les explains that Satan took Jesus up into the Holy City and set him on the pinnacle of the temple, with all the temple crowds down below. The temple pinnacle was not as high as some modern skyscrapers, so it was no problem seeing someone up there; it was easily within eyesight. Satan then tempted him to cast himself down, quoting that angels would bear him up. Les interprets this as the lust of the eye and a showmanship event, like a Madison Avenue advertiser imagining angels sweeping down to catch him before hitting the ground, and what that would do to the crowd. Jesus refused, saying, thou shalt not tempt the Lord thy God.
Then the devil taketh him up into the holy city, and setteth him on a pinnacle of the temple,