FtH with Son's of Inferno is a bug. As for the city, it's pretty ridiculous but I enjoy it. Makes conquering the lair something deserving of a trophy. I play on deity with raging and barb world so I definitely feel your pain. I do not want it changed but perhaps I am just masochistic.
For me Conquering Acheron's Lair is something to do at the end of the Mid-game, before I invade the huge powerhouses, to make that final invasion much easier.
For instance, imagining taking about 10 turns or so to Dominate the 10 Sons of Inferno. (using Archmage, Hemah, or Gibbon, + Royal Guards)
personally I prefer Gibbon with Mind III and Metamagic III
then, you have three Archmages, and if you have 4 of mana X, once dominated they learn that spell TOO!!! Its pretty much awesome.
