The church was already correctly set as nbr 50.
The number was not visible on most maps because this building also have a name (Pfarrkirche St. Joseph); in that case the software chooses to display the name and not the address.
There is a (complicated) method to make it work, i.e., transferring the address to a node, ideally on the main door. It worked here because the door was already mapped here: https://www.openstreetmap.org/node/5637101388