I have read the fyjs link. In it there is another photo of J-20 model in the same photo set.
In the background on the glass door, there is texts "中航城市广场", which translates to "CAIC City Plaza". A baidu "pedia"
says that it is a CBD building open to be rent. It is developed by CAIC owned property developer.
Another photo shows J-31 naval model
On the right side the plate says "If needed, ???????" I guess, the rest of the texts are "please contact xyz".
My conclusion is that, the photos are not taken inside CAIC, these models are there as advertisement by model making companies (related or not related to CAIC), they do not confirm or deny anything. I am not going to say the existence of naval J-20 project is legitimate or not, but I must say that the location where the picture of the model was taken does not add any legitimacy to support the existence of an ongoing naval J-20 project.