The recipe for triphenylphosphine creates 6 chlorine worth of salt, but only requires 4.

The chlorobenzene uses 2 chlorine, but gives back HCl (i.e. net use of one chlorine). The phosphorus trichloride uses 3 chlorine. i.e. 4 chlorine total

An easy fix would be to change the sodium requirement to be 4 and the salt output to be 8.