Within Calendar Manager, there is a section devoted to importing the calendar via a spreadsheet.
If your spreadsheet has been successfully imported, you will get an on-screen message telling you so.
However, if you go to the History section, you will not see your import listed and this list has not refreshed. The only way to force this tab to refresh is to go to anohter tab in the module and then navigate your way back to History.
It would be great if the History section refreshed when a spreadsheet has been successfully imported.