I'm not able to reproduce any issues with your library. I synchronized the library to a folder on Google Drive and it completed with no errors. I imported a new file, synchronized again and it completed without error. So I'd like you to clear out your sync folder, sync the library again and let me know if you continue to have issues with any future changes you make. I also would very strongly suggest creating a folder to sync to instead of synchronizing to the root folder of your Google Drive account. MobileSheets can create a significant number of folders during the sync, so it will prevent your Google Drive folder from getting overwhelmed with all the folders.
Mike
Mike