Landgasthof Hotel Zum Storchennest is in Mommenheim, Germany. It is not in Mainz, Germany.
The article has the correct address, but it is listed under hotels in Mainz??
There is not even a listing for the city of Mommenheim on Travel Advisor. There are listings for the small towns around Mommenheim (Harxheim, Selzen, Lorzweiler), but not Mommenheim. Mommenheim is 15 km south of Mainz
You just need to remove the Mainz from it and make it in the city it really is in.