Except you don't have access to game state in these cases so there's no adjustment that can be made.
You can only move forward in the frames you display. You can't walk back in time to evaluate a player's action in relation to their latency and then reconcile game state with all other clients.
Yes you can. When the server sends the "official" record of moves made, if the client detects any discrepancy with expected results, it resets the game to a slightly earlier time and replays the "real" moves to reach the current point. All this is done instantaneously, and only at the end is the interface refreshed.
> resets the game to a slightly earlier time and replays the "real" moves to reach the current point.
That's exactly what properly engineered network games do. However we're talking about video streaming here, in which you don't have access to any game state. It's not possible to do without the developer going in and adding specific feature support for your streaming service.
You can only move forward in the frames you display. You can't walk back in time to evaluate a player's action in relation to their latency and then reconcile game state with all other clients.