When you export a structure to Excel, the time tracking information is shown in hours format instead of your Jira duration format (e.g., 1w 3d 5h 20m).
Below is the Macro and instructions you can use to convert this data into a string of that format.
Only Excel 2010+ is supported. It is possible that the macro will work with the 2007 version, but we can't guarantee it.
Download the attached Macro: FormatTimetrackingData.xlam.
In the dialog, click the 'Browse' button and select the downloaded FormatTimetrackingData.xlam
As a result, selected cells will have General format and will contain a string in the Jira duration format like "1w 3d 5h 20m".