At this point, the ribbon and the context menu are not localized out of the box and the users need to change the strings manually.
Hello Julio Cesar,
Thank you for sharing your feedback.
All the strings in the control are in English. However, if you need to switch between English and Spanish, you will need to customize the XAML of the controls with the corresponding localization strings. Please, continue following this item so we can notify you when its status changes.
Regards,
Tanya
Progress Telerik
I think it would be very useful if it could be shown in different languages.
At least in the most common: English and Spanish.
Its component is very powerful and useful so that only you lack that.