There is a separate tech for Henchmen. Henchmen are no longer unlocked by the Heroes tech. The only requirements to build Henchmen are Altarian blood (Men race) and the Henchmen tech, which is underneath the Heroes tech. I have a custom Altarian faction in 1.02 and I researched Henchmen tech and was able to train Henchmen. You don't need Heroic tech for Henchmen anymore, it is now a characteristic of the Faction Race, like Slaves are for Magnar, Juggernauts are for Yithril and Iron Golems are for Gilden. Heroic tech just gives you influence when you complete quests and extra experience when you complete quests, and maybe one other bonus.