To reproduce: 
1. Drag and drop RadColorBox
2. Add localization provider. Use the following article http://www.telerik.com/help/winforms/forms-and-dialogs-colordialog-localization.html
3. Open ColorDialogForm and choose color which name was localized too. Close the form 
54 You will see that the text of RadColorBox is not localized name, it`s system name. 

Workaround: 
1. Subscribe to the ValueChanged event
2. Replace the text of RadColorBox with localized color name

void radColorBox_ValueChanged(object sender, EventArgs e)
{
    string localizedColor = Telerik.WinControls.UI.ColorDialogLocalizationProvider.CurrentProvider.GetLocalizedString(this.radColorBox.ColorDialog.SelectedColor.Name);
    this.radColorBox.ColorBoxElement.TextBoxItem.Text = localizedColor;
}