Unfortunately, there is currently no way to change the FMOD Engine’s random seed mid-way through a game session.
As such, if you want to be able to synchronize which playlist entry of a multi instrument will play across multiple clients, there is no way to do so; the only workaround is to remove the playlist entries from the multi instruments and instead control which one plays using parameters whose values are synchronized and randomized by your game’s code.
Thank you for pointing out this limitation of our current system. I’ve added a task to our feature/improvement tracker to support changing FMOD’s random seed mid-game, so that there will be a simple solution to this issue in future.