I have fiddled about with the game files a bit and managed to get the CAS Demo to recognize copies of traits and ambitions. For Sims 3 these things were a pain to add as the system relied heavily on enums and hard coded data, but from the looks of it this seems to be changed for the Sims 4.
For anyone interested I have an image to illustrate:
As it seems we know have a Guru participating in the forum I want to ask a simple question:
Assuming all related resources and scripts have been created is it possible for modders to add content such as careers, skills and traits to the game?