It looks like Xian develops heavy aircrafts and bombers. Being located in the deep interior of China, it enables better security and weapons testing. China tends to locate strategic assets in the interior.
Transferring projects to different institutes that are assigned more appropriate specialization is common practice with the state owned Chinese aerospace sector, or at least was in the mid 2000s. My guess is that if these developments are true XAC was given the project because XAC has the most experience with bombers.
Are you sure that photo is legitimate? The definition and interface between the bottom of the airframe and the background photo of the venue don't seem to match, let alone the lighting. Looks photoshopped. Also note the landing gear protruding from the bottom looks like it belongs to a different aircraft, looks like a concept CG pasted on top of a demo of the J-31.Assuming the black model has two men cockpit, therefor the size of the windshield is in similar size as Su-34, you can see that the JH-XX is much lager in overall size.
So even if the cockpit mockup looks the same size as Su-34 or F-111, it still could be the JH-XX's cockpit.
P.S. JH-XX model is certainly larger than Su-34 or F-111, but it is not that much larger that you may expect. After all, it is a JH.
