The ghoul almost teleport and even pass through walls
Ghouls pass through walls, because there is no pathfinding in the game yet. They would get stuck on anything otherwise.
They shouldn't be teleporting though. They only reset their position when you leave and enter the area and they incredibly fast once angered, but should be it. What exacly do you mean by teleporting?
I couldn't replicate ghouls teleporting around. They always spawned on one spot and then started slowly walking towards you. I was switching areas, killing them and leaving areas, passing a week and coming back and they always spawned at the same spot.
Is it a specific location that does that, or some specific action?
My theory is that because of the darkness and the fact that ghouls home on you from the start (They don't have a cone of vission like other enemies. They always know where you are and are always chasing you) makes them look like they are teleporting, which isn't the case when you get rid of the darkness.