EB is optimized for VH campaign M battle. The Medium in battle will give you enemies that are roughly equal. Any higher setting will give the AI morale bonuses that will allow AI levy troops defeat your elites.
The easiest way to avoid Sweboz juggernaughts is to use one of the EB money scripts. The thread and the files can be found on the Unofficial Modding Subforum. The money script balances out the factions and prevents the AI from fielding the legendary "Stack perades" of countless elite stacks during the same turn against the player.