I just fix another problem with order confirmation takes too long, it takes about a month for me to figure out. After adding all files to mails/en folder( 2 other was actually missing order_conf_cart_rules.tpl and order_conf_cart_rules.txt), I still had same issue. Then I open classes/PaymentModule.php and set DEBUG_MODE = true; in the beggining of this class ( it will log all actions to backoffice Log tab).
What I found : After 'Hook validateOrder is about to be called' it takes about 5-8 minutes to get next step
'Order Status is about to be added'.
So I look at my payment module stripjs and didn't find any registration of 'actionValidateOrder' hook and no function with same name. Only module active which is use this is mailalert module.
Next my step - commented line 644- 650 (/*Hook::exec('actionValidateOrder', array(
'cart' => $this->context->cart,
'order' => $order,
'customer' => $this->context->customer,
'currency' => $this->context->currency,
'orderStatus' => $order_status
));*/
Create order and finally success !!!