I wouldn't worry too much Harald. Whilst it's not unknown for Duratecs to swallow swirl flaps the usual gradual failure is their bearings which lead to rattling and vacuum leaks rather than immediate engine destruction.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone