IIRC, there have been no photo of any guided ammo on the four ventral hardpoints. We have only seen dumb bombs and targeting pods on these points. Hence the speculation that it is because these hardpoints are difficult to wire up.
I could be wrong but I imagine that, during wars, this kind of adaptors will only need to be wired up once for a J10 to do multiple sorties.
I think PLAAF's doctrine probably does not require J10 to carry more than 4 mid-range AAMs in A2A. For A2G, the requirements might be different. As we are learning from the Ukraine conflict, PLAAF needs to use more guided weapons for A2G. In the Taiwan scenario, if J10 would be able to take more A2G missions, there would be more Flankers, J16 in particular, for A2A or longer range A2G missions. In longer term, J10 could even be turned into dedicated A2G aircrafts.
Now I agree that this adaptor would not be for A2A as it would require integration with the airplane's radar and FC.