On the 777 it’s 10degs/85% or 4degs/70%.
It seems foolish to me to increase pitch and reduce thrust if we notice that our airspeed is unreliable. In fact it might be downright dangerous.
I think it has to be reiterated that these figures are not expected to produce level flight or cruise airspeeds. Just something that keeps you inside the flight envelope while you diagnose the problem and get the QRH out.
One thing is pretty much guaranteed: the failure will catch you by surprise and it will be of a type you haven’t experienced before. It will probably interact with auto systems in a “interesting” way, too.
So far none of the aircraft manufacturer(s), Mr A nor Mr B nor Mr E, appear to mention checking that the Stab Trim is somewhere near where it should be for the configurations.
A good point. Maybe it is assumed, much like stick/yoke forward, houses get bigger, stick/yoke back, houses get smaller then bigger again? They do mention trim when it comes to upset recovery, which could be needed if the UAS scenario has been in play for a while until noticed...