At first glance it does look reversed. Once you know the hammer gets cocked by sliding forward and fires when released to the back, it will make since. Hopefully anyway.
The hammer slides to the rear striking the breech slide, the breech slide then pushes on the tank valve releasing air. Then you slide the breech slide forward, allowing you to insert a pellet and cocking the hammer at the same time. Pull back on the breech slide and your ready to go.
Hope that helps, it is kind of backwards but it gives a straight line for the air to travel, no bends, etc.