NHF – new heroes for Heroes V 3.1.

Will Kujin definitely have a bonus for them? Maybe her special ability works based on ID, not the "demon" characteristic.

I just checked. The specialization only works when there are infernal units of that race in the enemy army; having them in Kujin's army, as well as having other non-infernal demonic creatures on the battlefield, does not affect her rage.
Her special ability turns out to be quite unclear.