Problem Description
When you uploaded excel file to Confluence, and use Viewxls macro, the Date format will be reverted to US even though the format cell is already in other locale. This will only replicated when the Windows locale is the same with the one in Excel.

Steps to replicate

1. Change Windows Locale to Other language such as German
2. Create an Office Excel file and enter date “31.12.2012” in cell A1.
3. Check the locale and you will see that the Language is already in German.
4. Save the file.
5. Upload the file to Confluence
6. Use Viewxls to view the file
7. You will see that the date will be reverted to US format