Legal Question in Criminal Law in California

I am not sure I understand your question. As I understand it, you share a room with another person. A search warrant was issued which allowed law enforcement officers to search your roommate's room. Since you share a room with your roommate the officers in the process of searching your roommate's room necessarily searched your room since the two of you share one room.

Yes they can search the room but they cannot search items that are unquestionably yours. For example if you are female and your roommate is male and there is no evidence of cross dressing the officers probably cannot search the pockets of dresses found in your closet.

There is no requirement that the warrant be shown to the owner of the house.