I've said plenty of times in this thread and the previous comments that there's nothing whatever to prove a link between the horse and the sun, so no agenda here.

My argument with your argument (!) is that it seems - to me anyway - to be based wholly on precise alignments and orientation viewed scientifically, with your knowledge of the movement of the sun to the fore in your thinking. My perception of this discussion is that you're considering the horse as a statically aligned object, in a fixed position and orientation. Whereas I think there is scope to consider the artistic intention more.

In any well-realised depiction of a person or animal running, your eye is always going to be drawn to the place that its motion is taking it, and where it is going to go next. You aren't going to view it as running on the spot, fixed in place, or the artist has failed to convey forward motion properly.

In this case, the horse is running to the right, along the side of the hill. The horse itself is broadly aligned to the SSW above the manger, but the hill that it's running along is actually generally aligned much more the SW (in fact it turns WSW) and this is the general direction the horse is galloping along as it rounds the contour. Anyone running along the hill in the same direction as the horse would follow the crest to the SW as it contours round the manger.

And it's probable (not factual and not proven, but probable) that the horse has been designed to be seen from a distance, and that you can only see it properly if you are looking at the hill from the vale.

And for anyone viewing the horse from a position where its horsiness can actually be seen, the sunset will be to their right.

You can state factually that the horse isn't aligned on the sunset, I don't dispute that in the slightest. But I would argue that it can still be interpreted as running towards the sunset as it follows the hillside along. That doesn't make it a sun monument, or create a provable link between horse and sun. But I think it is too narrow an interpretation to ignore the artistic intention of forward motion and view the horse and its direction purely in terms of angles and alignments.