Don't think that they are temporary or they would have been removed by now. But they will be beyond vision, if you are looking at the pitch and not looking up at the roof
The only person who can enlighten us on this is a bona fide structural engineer, otherwise it is purely guess work. Me being Mechanical, structural is just guess work with some knowledge of the structure of steel wire ropes.
Give over, they are for sitting on. In normal circumstances only the ground staff will be seeing them. So why worry, on match days there will be bums on them seats. HOPEFULLY.