OAP,
I think you’re being a bit naive by expecting questions such as yours (‘can Typhoons operate in the face of S400?’) to be answered in the public domain. Generically, I would expect a CAP to have been placed to deter Syrian or Russian ac from making westbound excursions that might have threatened the Tornados at the easternmost point of their routes (which wouldn’t have been very far east in any case so the CAP could easily have been filling a ‘detached escort’ function overhead Akrotiri). This would also have deterred any potential threat to Akrotiri itself. While the Tornados would have been able to fly under the S400 radar horizon, that wouldn’t have been an option for an effective CAP. As such I don’t think we can infer anything about the Typhoon’s capability or tactics from the publicly-available information - exactly as it should be!