Does State Parlor give bonus for dwellings added after the fact?
In the revised English language appendix (page A5), it states (all bold and italics in the original)


  When building the State parlor, immediately (and only once) get 2 Food from the general supply for each Dwelling that is (horizontally or vertically) adjacent to the State parlor.


This unambiguously indicates that later dwellings do not provide a further 2 Food bonus. The same language is used for the milking and weaving parlors.