Have tried your approach created a Webhook with the order.updated as action.
Now ordered a product. And did the following
Changed the status from the following buttons.
But the webhook didn't fired at all.
Then went to the respective order and added some custom field value and clicked on save order.
Then checked the Webhook log. Yes for this above action a webhook triggered.
Now i tried with changing the status of the order from the order edit page itself.
Here changed from processing to on-hold status and did save order.
(Status processing was set previous while trying to update status from the order list dashboard itself.)
Again checked the webhook log for the same.
Yes and now the webhook had one more trigger logged in it.
Finally got to a conclusion that this order.updated action is triggered when any changes are made and saved view the editing the single order page.
A Collaborator has suggested to use action.woocommerce_order_status_changed instead.