Hmm, why would N2 be the free turbine? I would think the low spool would be the power turbine and the high spool the compressor turbine.
The problem is I guess that MSFS doesn’t see the power turbine completely separate? On a turbofan the low pressure compressor and the fan together form the low spool. Is it possible to create a triple spool turbofan in MSFS? Then the low spool could be the gearbox output axis while the intermediate spool is the power turbine (gearbox input) and high spool forms the compressor spool. In the real PT6 there are only 2 spools of which the power spool is connected to the reduction gearbox so maybe this can be simulated somehow with three spools?
Just thinking out load, I have no idea how all of this MSFS stuff works. I would think MSFS considers N1 and N2 as being part of the compressor system while N3 is never part of a compressor system (in real life) and only drives the fan on a triple spool turbofan. Maybe a gear ratio of 1:1 between N1 and N2 so they are basically one single spool? And then N3 forms the propeller.