FISA Improvements Act of 2019 This bill makes various changes to the Foreign Intelligence Surveillance Court, such as by requiring amicus curiae (i.e., outside parties that assist in consideration of a case) involvement in certain matters. An amicus curiae shall assist the court when it is considering an initial application seeking permission to target an identifiable U.S. person for certain types of foreign intelligence investigative activities (such as electronic surveillance or a physical search). An application to the court for an order for electronic surveillance shall include a statement fully disclosing any information used in the application that the government cannot substantiate. The bill also requires transcriptions of proceedings before the court. The Department of Justice shall maintain all written communications with the court and written summaries of oral communications with the court.