As mentioned in the description, it allows them to choose what happens in 'account settings'. However if you have set it not to show in account settings, there is no way for them to set this. The only other option is for it to do nothing. If you want it to always sync, you should be setting it to always update local database, but as mentioned you cannot do this at present because of other settings.
In terms of synchronising other items, there is no option to add things in. For that you would required a custom solution.