Hi,
The end view is called after you click on the "finish" button of the checkout. So this one will always be called when an order is created. But the order is likely not paid at this point.
The after_end view is called after the payment when you're redirected back to your website. But based on the payment plugin you're using and how your payment method is configured, the view might not be called.
The best is to not use a view override. Instead you can develop a plugin and implement the onAfterOrderCreate and onAfterOrderUpdate events of HikaShop, check the status of the order, and based on this, use the offsite conversions tracking to report the sale to Facebook:
developers.facebook.com/docs/meta-pixel/...-offsite-conversions
This way, regardless of how the user is redirected back to the website, the payment plugin being used, etc, the orders will be properly taken into account.
That's actually what we do with the Google Analytics and Matomo plugins available for free on our marketplace.