The best you can do is add your own notification to the application. The Create dockpane "built-in" message is not accessible.
var feature_name = "Parcels";
ArcGIS.Desktop.Framework.FrameworkApplication.AddNotification(
new ArcGIS.Desktop.Framework.Notification() {
Message = $"Create {feature_name} complete",
Title = "Create features",
ImageUrl = @"pack://application:,,,/ArcGIS.Desktop.Resources;component/Images/MarsCat32.png"
}
);