In France usually hiking signs aren't oriented to cardinals directions.

The destination:arrow tag show only if the arrow point to the left or to the right of the  finger (See https://en.wikipedia.org/wiki/Fingerpost).
Or how the arrow is painted on the sign (See  https://wiki.openstreetmap.org/wiki/Key:destination:arrow)
Real directions of each "finger" could be in ai.e. something like destination:direction.

Yves