Late-game Town Enhancement.

Could you please tell me where the balance lies for the Tribes of the East if the map is huge, and the meeting time is 5-6 months against Orcs, Dwarves, Humans, and Inferno? It seems like nothing can be done.

For the Tribes of the East, the entire strategy should be focused on meeting as early as possible.
The opponent will likely prepare against the Tribes of the East and reduce the damage from spells.
Against Orcs, the only option is to use Darkness and look for subordinates, Berserkers, etc., so that they kill each other.

Well, and you might have to resort to a not-so-nice trick:
Create a group of heroes with high Chaos and Dexterity skills (mentoring will help) and attack them before the main hero's battle.