Hi Riccardo,
Thanks for using Syncfusion Product.
At Present we do not support localizing Tooltip in PDF Viewer Control. We have logged a feature request for the implementation of the same. We have created an incident for you to follow up the implementation of the feature. Please login to your account using the below link to access the incident.
https://www.syncfusion.com/account/login?ReturnUrl=/support/directtrac/incidents
As an workaround we can use the custom tool bar sample and provide tooltip in the local language. Please find the sample in the below link where we have provided the tooltip in German language.
http://www.syncfusion.com/downloads/support/directtrac/141632/ze/Custom_Toolbar1459760012
Please let us know if you need further assistance.
Regards,
Sathish
