OK, let's make up a theory.
I will assume, based on nothing, that during the the build up of power just before the discharge some vibration is created (at the natural frequency of vibration of the energy crystals).
In order to keep the energy golem targetted, it stands on a cross-shaped platform (like a + sign) when looked at from the top. When we look at it sideways, it's V-shaped. This limits the vibrations to be mainly in the vertical direction, but the golem's heavy weight (Dorgon is slow, remember) makes the vibrations of small amplitude and not affecting significantly the accuracy.
The cross shaped platform allows to turn the golem to only one of 4 directions at a time, fixed before the battle by the mechanics to the directions where the enemies will most likely come from.
The golem has an hydraulic mechanism that helps it rotate in the base, but the heavy weight of the base, where the energy capacitors are stored, makes it difficult to move the golem significantly during the course of the battle or even rotate it.
Some attempts to create golems on a free rotating platform were made, but the vibration during the charge up phase made the firing accuracy terribly low, so that idea was discarded.
Instead of it, some wheels were placed below the base that allowed movement on one direction. Later on, a prototype where a steam engine was connected to the wheels tus allowing movement was created, and Dorgon was born. Note that moving the wheels at different speeds we can rotate Dorgon in any direction. However, Dorgon's targeting system is the best we can find in energy golems. This system is made to fire in only 4 directions, so Dorgon cannot (at the moment) follow a target and fire at it out of the 4 main directions.
End of the made up theory.
