Log linearize the cdf in non-linear perfect foresight model

Dear all,
I am trying to change some aspect of a nonlinear perfect foresight model. However, the model is quite sensitive for changing. In the model, there is the cdf function. My plan is to log linear the model and hope for a better result. But i am not sure that can i do it with CDF. Thanks a lot for your kind helps.

What do you mean with quite sensitive? Also, note that there is a linear_approximation-option to perfect_foresight_solver.