a double rail on existing pylons would be more effective then wingtip rail, for aerodynamics, design, modification period, cost, and performance altering to aircraft.The J-10S is not the trainer version, it's an 2 seater attack variant ! In my opinion, they have a different philosophy for training, if you look carefully at the time when J-10S made it's first flight (December 2003) and the first regiment being created (August 2004) there is only 8 months, you can't train that much pilot in that less time ! Forgetting that this J-10S prototype was used for development and then making any use for training impossible.
As for CFT's, we could suggest that eventual J-10BS could have them since he's mainly oriented for A2G role.
Also last question, how about wingtip pylon ? It would be useful for J-10 to get a comparable loadout has the F-16.