Localization
The HTML5 Viewer component supports the complete localization of its interface. To localize the report viewer interface, use the special Localization property. As a value of this property, you should specify the path to the localization XML file (relative or absolute).
Default.aspx
...
<cc1:StiWebViewer ID="StiWebViewer1" runat="server"
Localization="Localization/en.xml">
</cc1:StiWebViewer>
...
When you load the report viewer, the localization file will be loaded automatically.