You haven't heard my opinion. You've heard what the law says. My opinion as to what your employer should do or whether they are acting fairly or not has nothing to do with the legality of the situation.
The legal answer to your question, which is I assume what you want since my opinion and a dollar will get you a cup of coffee, is that your employer is not legally obligated to return you to work once your 12 weeks of FMLA is used up.
FMLA is a Federal law, not a California law. It has been a Federal law since 1993. California is subject to Federal law. There is no validity to your contention that FMLA did not exist in CA until July 0f 2004. CA implemented a paid leave policy at that time, but it was not FMLA, which had already existed in California and all other states for 11 years at that time.