There should be no need to track anything in Plugins/FMOD/Cache/ as this should be generated programmatically. You should be able to force cache creation with a call to FMODUnity.EventManager.RefreshBanks at the start of your build script. Can you please try adding that in and let me know if that helps at all?
If you could also please tick Enable API Error Logging, set your Logging Level to “Log” and send me the output of your build log, that might reveal some more information on what’s failing.