Hello,
Apologies about the Inconveniences caused!
We have checked your Forms and codes you are using is entirely customized. The Default include/form.php that comes with Canvas is not used anywhere, which is why "Please set a Message" Notification is displayed. This unfortunately, will not work the way you want it to, as nothing is used according to the Default Files or the Documentation. The Default Files work just fine: http://themes.semicolonweb.com/html/canvas/contact.html with the Spinner and Notifications showing up by default. There are multiple examples available for Custom Flexible Forms as well: http://themes.semicolonweb.com/html/canvas/forms.html .
The Forms Processor included with Canvas is very powerful and is already capable of processing all the Custom Input Fields. However, If you must use Custom Processing Codes for your Forms, you will need to use a JSON Response, like this:
echo '{ "alert": "success", "message": "Form Submit Successful!" }';
exit;
for the Notifications to work properly. Else you will need to Customize the Entire Functionality manually without using the .form-widget DIV. Because, as mentioned earlier, we currently do not provide Customization related Support according to the Item Support Policy: https://themeforest.net/page/item_support_policy . You will need to manually code this or Hire a Freelancer to help you out. If there is a bug with the Default Codes or something is not working as it should, as provided in the Default Files, we are more than Happy to Help and provide you with a fix.
Additionally, The Documentation > Forms Section provides complete information about using the Forms, setting Custom Messages and Customizing the Alerts. So we would request you to go through it as you might not need to Customize the Forms Processor at all. However, it would be great if you can please let us know which part of the Documentation was not useful for you, so that we can make improvements. Thanks for your Patience.
Meanwhile, do let us know if we can help you with anything else or if you find any further issues with Canvas.