Your script is making an ajax call to a Script Include called 'GetInternalExternalCSM' which is not available to us. It seems to return "internal" and "external" properties, which are used to set the form properties.

I still believe our investigative approach would've eventually revealed why g_user.hasRole('snc_external') wasn't returning the expected values when an external user was logged in. I'd prefer using g_user.hasRole('snc_external') since it provides a simpler and cleaner way of determining the user role. You might continue looking into it and it might reveal a few things that can help you down the road.

Good luck!