Thank you for contacting us.
Unfortunately the Filter Window hasn't had full localization yet. However we are working on PivotGrid localization and for the next Q2 2013 we will add localization for all build in controls’ texts. Currently all controls texts can be set to values different than default via RadPivotGrid.FilterWindow property.
Please excuse us for the temporary inconvenience.
If you need further assistance, do not hesitate to contact us again.
All the best,
the Telerik team
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