Hi Josep,
Thank you for contacting Syncfusion support.
In SfRibbon, you can localize the text of the BackStageButton directly using the “BackStageHeader” property and tooltip of the BackStageBackButton can be localized by follow the below steps
1. Right-click on the project, select Add and then NewItem.
2. In Add New Item wizard, select the Resource File option and name the filename as Syncfusion. SfRibbon.UWP.Resources.<culture name>.resw .
3. Add the Name/Value pair in Resource Designer of Syncfusion.SfRibbon.UWP.Resources.de.resw file and change its corresponding value to corresponding culture.
4. Application culture can be changed by setting CurrentUICulture before InitializeComponent()method.
We have prepared a simple sample in which we have localized the values of BackStageBackButton ToolTip and BackStageHeader and it can be downloaded from the below location.
Regards,
Keerthana J