Child custody Sacramento County CA & FCS mediation inaccurate reporting

My fiancé got temporary custody of both his children due to an assault on his oldest child by mother's fiance while mother watched and did nothing. Now have been fighting for custody and Sac CO mediators (have seen two different ones) do not address mother's felonies (for child abuse and inflicting corporal punishment on child) do not address mother's mental issues and history and does not address her drug abuse and is recommending youngest child go back to mother. 2nd mediator read 1st report and made recommendation. Judge doesn't seem to care that these reports are incorrect, or that these reports are slanderous. She seems only to be siding with mother. Father has an attorney; judge doesn't seem to give credence. What can we do? Can we have the hearing changed to a different judge?