If you’re looking for a real sync solution you may try our app DAVdroid. You need to set up a CalDAV server first. Then you will be able to synchronize your calendars in two way. DAVdroid is open source and it published under GPL and we also sell it in the Google Play store, because it was and is very hard work to write and maintain it.
@armadillo Synchronizing events (and tasks) is a very complicated task and it’s not done with simple copy operations. All the complex operations and requirements are best covered by a separate protocol – as CalDAV.