Not familiar with the Bus so forgive me if this seems a simple question to someone.
Would the Mach Trim have been affected by the loss of the ADIRU, PIRM 1 and SEC 1 etc ? I'm assuming given a loss of Pitot input the systems will have no idea where the aircraft is in relation to MCrit / MMO etc and would therefore not be able to adjust the Mach trim as Mach increases? I'm thinking Mach Tuck as another possibility to the stall / spin scenario?