Not speaking for hashfast but for rackmount servers airflow always has to be front to back without exception. A datacenter is going to use hot and cold aisles and they aren't going to reverse the flow on an entire row of racks (up to 400 servers) to accommodate a special request.
So either HF would need to put the modules up the airflow will be radiator first. My guess is they have no choice but to have radiator up front because 2U is only 3.5" high that probably means the radiator is no more than ~3" tall. A 19" case is ~17.5 wide but putting it in the back means losing 4" of width to the PSU. Not sure a 13" by 3" radiator is up to the task of dumping 750W.
Still your right the photo seems to directly contradict the description..
That's my understanding (front to back) which makes me assume the text statement of radiators being rear-mounted is the intended design. However, it then raises the question of why the render shows the radiators mounted in the front. It would be my guess that the sizing of the radiators would have to accommodate the placement of the PSU, and if the renders are any indication, then they have not accounted for PSU spacing and the radiators will in fact be at the front. There appears to be two rows of radiators, but I'm not versed enough in liquid cooling to speculate on whether dissipating that volume of heat is feasible given the approximate dimensions of the intended design.
Edit: Changed to discuss your longer post.