When adding rows to an excel file, or copying an excel file in a sharepoint folder, the operation is performed asynchronously. This causes errors if adding multiple rows or copying the file immediately after submitting add rows requests, as the add rows requests may easily overload the server, fail behind the scenes and/or the copy operation is processed before the add rows requests are complete.
All connectors should have a clear synchronous or async mode, as available for the service. If either method is not available, the connector should so indicate. It is not clear what operations are processed synchronously vs async.