In the approach you have provided you are setting only the CellEditTemplate, which is applied when the cell is in edit mode. You can try setting the GridViewDataColumn.CellTemplate instead. Furthermore, it seems like you are trying to directly set a font in a DataTemplate. Instead, you need to apply the font to a certain element like TextBlock, as shown in the provided article.
Regards,
Stefan Nenchev
Telerik by Progress
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