Thank you for your feedback.
Web search suggestion
Check this page for detailed format documentation. Listary is only interested in the 2nd element in the response array - the completion array.
You can use this Google auto-completion URL to see some real responses: https://www.google.com/complete/search?output=chrome&q={query}
See if you can find the suggestion URL of your website directly on Mycroft Project.
Extension
Extension support is still incomplete at the moment. It will be ready soon.
If you really want to play with it now, modify C:\Users\YOUR_USER_NAME\AppData\Roaming\Listary\UserProfile\Extensions
. You need to restart Listary.