This paper studies downlink multicell cooperative transmission with imperfect CSI sharing led by backhaul latency, assuming full data sharing amongst coordinated base stations (BSs). Different from the traditional centralized cooperative transmission systems where multicell precoder is designed at a central unit, a so-called BS-processing system is considered, which enables a decentralized design of multicell precoder at each BS. We show that the resulting precoder design problem falls within the framework of team decision theory, based on which a decentralized multicell precoder is proposed, aimed at maximizing the weighted sum rate. We evaluate the performance of our precoder through simulations.