It's an inherent flaw of FSX to give way too much ground friction. This value may also differ on the actual surface you are on. Not speaking about some grass strips, but the variants of the hard surface in FSX.

So you will always see too high N1 values for taxi and the 'wrongness' differs a bit with the location and its surface. Some other devs tried to cheat that behaviour with custom engine models and things, but the success isn't that clear in my eyes.

I really doubt that reinstalling FSX helps or that a wrong installation of the CS plane triggers the wrong behaviour. The ground friction stuff is fixed and the same goes for the values in the air file and the aircraft.cfg of the plane.

Can you try slewing her to another parking spot or even airport to check if the 50+ values are needed at all spots? I sometimes see the difference when I want to powerback with my prop planes. On the one spot it works, on the other it doesn't. Fuzzy logics.  :-?