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Reversible alpha floor and digital back up speed are two different things. Previously when AoA shown as speed on the tape, (it's ADR1+2 divided by 2) increased beyond a certain threshold alpha floor was triggered setting the thrust to TOGA and then locking the thrust at TOGA. The pilot then reduced the AoA and disconnected the TOGA LK , reengaged the ATHR and brought the thrust levers to CLB detent which is active ATHR position. So there were some actions that needed to be done otherwise the acceleration will continue leading to VFE/VMAX exceedance. Now this is automated e.i. when the conditions for alpha floor do not exist it's back to normal. Digital Back Up Speed deals with unreliable air speed it is a calculated airspeed or synthetic air speed as Boeing call it in B787 independent of the Pitot static system with some degraded accuracy. So the actions for ADR disagree are spelt out on ECAM and pilot just executes that. So no ADR Check procedure is necessary. A350 has a fourth pitot static in the engine which FADEC uses. That's known as alternate speed and the calculated speed is the fifth but less accurate option. The monitoring and switch over when required is automatic with only intimation to the pilot.