the chemistry is incomplete in the reaction you posted. Chem geek gave an excellent explanation of the full chemistry in this post.
In a nutshell what is not taken into account is that when chlorine is broken down or used up the reaction is acidic so the net effect is pH neutral. Hydrogen gas is produced at the cathode of the SWCG and this causes aeration of the water that causes CO2 to outgas. It is this outgassing of CO2 that is responsible for the pH rise and can be controlled by lowering the TA to lower the amount of carbonation in the water. This post might help explain why.

Your leak is not normal pool operation with a SWCG so while trichlor migh be of some use in your case it would not be for the majority of salt pools.