How should these units be tagged? From scanning the various wiki pages about buildings there doesn’t seem to be a consensus. house=terraced seems wrong because this is not a row, and tagging this as apartments seems wrong because each unit is separate, they just happen to share common walls.
Would tagging these as house=semidetached_house make sense?
I don’t see an issue with tagging house=quadplex. Using semidetached_house doesn’t work, as they only share one wall with another house.
If it’s essentially one building with several independent parts, you could use building:part to to clarify the relationship.
What about house=maisonette
https://wiki.openstreetmap.org/wiki/Tag%3Ahouse%3Dmaisonette
I don’t understand the fascination with the house tag. Besides knowing a building is residential use, what more does house=* provide that the actual geometry doesn’t tell anyway?
to me a maisonette is an apartment over several floors, here it seems that’s 4 attached houses? Or is it one building divided by four? E.g. are the floors over the whole or are they divided? What about the roof? Houses attached to another are not uncommon, IMHO to become a maisonette there must be also other apartments in the same building, or it’s a maison 
Maybe English usage is different?
Update: I have asked chatgpt and was told that while the usage in English to mean a kind of apartment ranging over several levels is common, there is also the usage to mean a standalone or semidetached house like a cottage in the countryside.
I’d just tag each building as an apartment building.
Thinking about this more I think this makes the most sense. If I were passing by this building in my car I would describe it as an apartment, just a single-level apartment.
