You could try to change the current UI culture before the InitializeComponent() method of the window where the RadGridView is:
This approach will set the default startup language of the control as it is explained in this article
from our documentation.
You may find useful to check the Localization demo, which is demonstrating how to dynamically change the language of the RadGridView. To test it, you could download our application for WPF
or check the Silverlight version
of this demo directly in your browser.
I hope this helps.
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