The right way to display link in Prestashop is by using methods of Link class. It is often used getPageLink method.

When you need to use this function from admin panel for front controllers - it will not use canonical form. All because Dispatcher object can be initiated in 3 states: front, admin and module. And front controllers’ routes are available only when dispatcher is called from front controller.

To overcome this problem you may add a custom getPageLinkCustom method which will accept as last parameter a controller type.