After clearing the spider caves, I used my mage's teleport ability to go to Angolwen. Upon leaving the city I ended up on a seemingly random square back in the West. (Fortunately I could go back east by reusing the portal in Moria).
A similar thing happened later in the game: I used the up stairs in the sandy dungeon where you teleport to Mt Doom, and ended up back on the West world map instead of East.
world map bugs after entering the East
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