I am not familiar with that engine.
I can empathize with the Germans on the engine's uncertain behavior as a training/readiness degrader.
Back in the early 90's, SH-60 family (B and F at the time) had some issues with the T-700 engine: uncommanded engine shutdowns.
There were a variety of electrical issues, signals crossing (related to the power sharing circuits) and wiring harnesses that sent spurious signals now and again. I remember (vagule) some diodes and seals were culprits for engines doing weird things.
It took a while for the engineers from
Marconi
Sikorsky
GE
all of whom had various subsystems involved in this lashup, to isolate all of the faults and find the fixes for them.
I will venture the following guess: the NH-90's engine issue will similarly get solved when the techs get their thinking caps on.