I tried it in debug using the radzen demo project and it work as expected.
The only thing i changed is the program.cs, i added the code to use the italian culture info
CultureInfo.DefaultThreadCurrentCulture = new CultureInfo("it-IT");
CultureInfo.DefaultThreadCurrentUICulture = new CultureInfo("it-IT");
CultureInfo.CurrentCulture = new CultureInfo("it-IT");
CultureInfo.CurrentUICulture = new CultureInfo("it-IT");
Thread.CurrentThread.CurrentCulture = new CultureInfo("it-IT");
Thread.CurrentThread.CurrentUICulture = new CultureInfo("it-IT");
Try clean the cache or check if ur browser (or maybe some extensions) have an
auto-traslate feature
Spero ti possa essere d'aiuto! Buon lavoro!