Dear @Muhammad.Sharjil,
If I understand correctly, you are taking the generator torque, generator power, and blade-pitch angles from one simulation with PCMode = VSContrl = 5 and inputting them to the OpenFAST S-Function of a separate simulation in Simulink with PCMode = VSContrl = 4. And while the blade-pitch angles generally look OK, the generator torque and power are off.
I’m not sure why the latter is so far off. Have you confirmed that the inputs are correct?
The extrapolation of the inputs to the OpenFAST S-Function in Simulink could be related to the small mismatch at the beginning of the simulation, as discussed in the following forum topic: S-Function input output signal mismatch.
Best regards,