place_id help with partially wrong information

It appears that you have stumbled on a bug in Nominatim; the address of that hospital seems to have some random bits in it that make no sense. I have reported that to the Nominatim admin asking to look into it.

Generally speaking:

Sometimes an object in OSM has an explicit address (i.e. we record "this object has this housenumber, this street, this postal code, this city"). This is described here: https://wiki.openstreetmap.org/wiki/Proposed_features/House_numbers/Karlsruhe_Schema. If such tags are wrong they can simply be corrected on the object itself.

More often than not, and this is also the case here, at least some parts of an address will be inferred - e.g. the post code from a post code boundary, the city name from a city boundary and so on. In these cases, if that data is wrong, it is good good to fix the incorrect polygons as they will apply to more than just that one object.

A place_id is always specific to one particular instance of the Nominatim geocoder. Your place id comes from OSM's Nominatim instance: https://nominatim.openstreetmap.org/ui/details.html?place_id=102283291 and you can see how the address is constructed there. It starts with "North Island" because there apparently was pedestrian area by that name encompassing the hospital; this seems to be an issue with Nominatim since there isn't (any longer) a "pedestrian area" tag on NZ's North Island. Probably this was a glitch in the data that has been fixed in the data a while ago and Nominatim hasn't updated. From this initial problem follow a couple other mis-assignments that make little sense. But normally, in a non-buggy scenario, you would find in this list a proper hierarchy going from the suburb or city quarter up to the country.