Hi, presumably the original position was based on previous slope preparations (last winter aerial images are from 2015). These can change every year and so the signposts for the winter hiking trails are also repositioned in the snow every year again. The Vorarlberger ‘Wanderwegekonzept’ and its legal handbook do not generally provide guidelines for attachment to house walls. Each individual signpost either has its own post or is attached to an existing public street lamp.
By the way, on page 62 of the manual, you can see a winter hiking trail sign attached to a wooden post.
Link: https://vorarlberg.at/documents/302033/472555/handbuchfuerdieanlageundb.pdf/d04f9244-79e9-aa35-54a5-02ec3c107d6f

