Hello, Mali,     

We already have a known issue about localizing column headers in RadGridView. You can track its progress, subscribe for status changes and add your comments on the following link : https://feedback.telerik.com/winforms/1370409-fix-radgridview-columns-headertext-is-not-localized-correctly 

Feel free to set the HeaderText programmatically according to the current language.

I hope this information helps. If you need any further assistance please don't hesitate to contact me. 

 

Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik