I cannot speak to the reason anyone would call "Alert Height" at 200 RA on a CATll approach. Alert Height is a term used in CATlll approaches. Sounds like an airline specific item. In the US the Alert height is usually a point at which the pilot flying states the intention to let the airplane continue the autoland, usually at 50'. Maybe someone else with a different perspective can chime in here?
"The TAC automatically disengages if engine thrust data is lost. Also, if the engine is damaged or surges, TAC disengages because ther is no accurate prediction of engine thrust. The TAC may still cause some rudder deflection in the appropriate direction, just before automatically disengaging". Straight from the Boeing Vol. 2 FCOM