Windows and Mac file paths are always different, you can't publish a live UNC path from Mac to Tableau Server. But you can do this:
1) On Windows, connect to the Excel file via a UNC path (not via the N drive) and publish a live pass-through data source to Tableau Server.
2) Update the workbook references to use the published data source rather than the network path.
3) Now you can edit and publish from Mac or Windows interchangeably as the path to the Tableau Server data source is OS-independent.