Legacy of Shantiri

Hello! I'm a somewhat inexperienced player, but after completing the first part (which I really enjoyed, and I experienced quite a few difficulties while playing as the hero), I wanted to play through the entire series of maps. But here, in the second part, I encountered a problem: after finally dealing with the orcs (which took 6 in-game months), two "plumbers" – Dark Elf heroes – emerged from the sewers, each with 400 Black Dragons, 300 Shadow Lords, etc. And their hero stats are 2-3 times higher than mine. Is this normal? Did I take too long? I have an army of about 50 Thunderbirds, 70 Rakshasa, and so on.