Thank you for your observation. I tried to map systematically all the buildings of Wildhaus with the aerial photo and the adresses after the Amtliche Vermessung from the Canton of St.Gallen. The "building" you are talking about has the offical adress Dorf 4 (see https://www.geoportal.ch/ktsg/map/40?y=2744760.33&x=1229774.56&scale=500&rotation=0 ). It's a long time ago I was in Wildhaus, so your local knowledge is very likely better. Feel free to improve Openstreetmap to the best of one's knowledge and belief.