The only time we mentioned Finstall was double asymmetric on the OCU. We then mentioned the drill IIRC
Pull the Flap Control c/b
Select 20 % Flap to get the high Rudder Boost pressure, apply and maintain at least 5˚bank towards the live engines.
Not necessarily in that exact order. I quit the OCU in 1982 so memory is not as sharp as it was.
Yep, the point of loss of control was when the sideslip vector masked the rudder.