Drupal Commerce custom Coupon Type not discounting
You may need to implement 

hook_commerce_coupon_granted_amount_alter

to add your granted amount to the display there.

e.g:

/**
 * Implements hook_commerce_coupon_granted_amount_alter
 */
function MYMODULE_commerce_coupon_granted_amount_alter(&amp;$amount, $coupon, $values) {

  if ($coupon-&gt;type == 'my_coupon_type') {
    $order = commerce_order_load($values-&gt;order_id);
    $order_wrapper = entity_metadata_wrapper('commerce_order', $order);
    $coupon_wrapper = entity_metadata_wrapper('commerce_coupon', $coupon);

    // Do stuff to get amount from coupon...
    // ...
    // ...
    $amount = 1000; // example
    $currency_code = "USD";
    $amount = commerce_currency_format($amount, $currency_code, $coupon);
  }
}