Nominatim seems to be ignoring a landuse with an address

[vectro]

Consider this way. It has a landuse tag and address tags.

However, a nominatim search for the associated address (23411 Summerfield, Aliso Viejo, CA, USA) does not return this way but rather the fronting street (Summerfield).

I'm not sure if this would be considered an error or not but I'm opening this issue because it's contrary to what I would have expected.

[lonvia]

The observation is correct. Nominatim only processes house numbers on POI-like objects: buildings, amenities, restaurants, offices, etc. In this particular case I would expect each of the houses in the estate have addr:* tags including addr:housenumber and addr:unit rather than the landuse.

That said, I've seen a few cases of landuses without houses really having addresses, for example parks in Canada. So it might be a good idea to create an artificial address point in such a case, so the address turns up.