If you start spilling air from the HPC in the case of an eng bleed vlv failure the turboshaft (or any gas turbine engine) surely tends to compensate this loss of air in burning more fuel ( FF rises ) in order to maintain the same Torque value, this causes a rise in ITT and as a consequence the rises of N2 so the torque lowers a little bit first then turns it back to the previous value....
Each time you ask the engine for a spill of air, you are requesting to that engine to spend more fuel to maintain the setting parameters......you want air, you don't want loss in power.