Legal Question in Real Estate Law in California

Maybe. The law requires agents to use "ordinary diligence" to keep their principals informed of their acts during the course of the agency (Civil Code section 2020). Whether an agent is required to divulge the contents of each and every e-mail or letter sent to or received from the other party's agent is doubtful, and you don't say that you are even sure any such written communications exist. You might inquire of the California Bureau of Real Estate, which has a consumer inquiries and complaints staff, and you could give them more particulars about what written communications you think exist and why they are important to you, as well as other facts. Ultimately, if this develops into a lawsuit, you would have the "discovery" tools of document-production demands, interrogatories and deposition in which you could seek relevant written information.