I decided to publish this find because the drawing is of such an unrivalled precision, almost to the fingernails. It's a characteristic of most older signs in Faeroes and Denmark (e.g. Children's crossing) only rarely found in other countries (find another one in Nepal).
The real Falling Rock signs all seem to be brought in from other countries, Denmark, Iceland or Norway, and mirrored to fit the local situation. It is therefore difficult to know which one, if any, is local breed, or how they traveled.