Hyperborea does indeed have east and west. Wherever you are, if you face Mount Vhuumithadon, then Helios rises behind you to your right, and it sets behind you to your left. Of course it never rises far above the horizon, peaking at only about 25° in mid-summer.

Rhebeqah wrote:

I think I worked it out. As an observer faces north they will see Helios appear in the NE. During the morning, Helios will move in a SW direction until at noon he is due south of the observer. Then he will move in a NW direction towards sunrise. My head canon does assume a convex Hyperborea which contradicts scholarly opinion in-universe but scholarly opinion may be incorrect in this instance.

That all depends on Where your standing in Hyperborea. Being flat, the presumption is that as Hyperborea turns "daily" the sun progressively alters position of rising and fall. Each "year" of the thirteen-year cycle the sun rotates it's rise and fall once around the flat disk. That said there is also a 7-year wobble arch that determines the height that the red giant comes into the sky.

So if you are standing near Kromarium at the height of Summer, it's likely that the noon sun would be behind you, the darkest days of winter, the sun would likely be in the distance north beyond the mountains. and not even crest above the horizon line.

But I could be totally wrong...