a MRGB driven permanent magnet alternator (PMA) powers the FADEC (with NR > 85%)
That would be NP, not NR.
It's actually N1 that drives the backup generator
For some of us (myself included) the memory is a bit weak; according to the BTA 407 Pilot Ground and Flight Procedures training notebook, "The Np (N2) gear train drives the PMA, the torquemeter, and the freewheeling unit." Its not N1 (Ng) or MRGB. Vaqueroaero wins a new 407!
