Do you enable "Localization Hack Status" 's check box ? If Yes:
Do you enable "DNN Nav Hack Status" 's check box ? If Yes:
Do you enable "Solpart Hack Status" 's check box ? If Yes:
Do you enable "Edit Tab Localizations" 's check box ? If Yes:
 

Click on the "Edit Tab Localizations" link. Select a tab to Localize.

In the row of "Selected Locale": choose the language you want localize. In Exemple: French.
Then write down the translation into the fields. Then update your change with the "Update link"(those 2 you mention) 
DO NOT use the "TR" button to update they are not use for that .

And the new text will appear into the "Applied localizations" 's row.

The change are now done so u can change language to check if it work.

Hope this help,
Joël