Unable to answer "What kind of building is this?" for way/227413186 via StreetComplete 53.3:

These are multiple buildings, most of them Appartments

Tecnicamente... Piazza DONATO Colombo, garibaldino.
(A Cristoforo è già dedicata una galleria altrove, poco lontano)

This looks misspelled and is not far from a similar POI to the south, is it real?

The place has gone or never existed. A user of Organic Maps application has reported that the POI was visible on the map (see snapshot date below), but was not found on the ground.
OSM snapshot date: 2023-07-10T17:38:00Z
POI has no name
POI types: amenity-post_box
#organicmaps

Here, from the side of Vico della Chiesa della Maddalena there is no park. Lokks more like a rooftop garden. The hostel location is correct, the hostel ius in an old building.

Salita Pietraminuta

way/684309915
Aggiungere Raffaele al nome della piazza

Unable to answer "What kind of building is this?" for way/226757122 via StreetComplete 53.3:

More than one house