At nowiki the parser function now returns English date formats.
At the test page (this is the birth date for Jim Hall) the date is written as "4 December 1930". It was previously "4. des. 1930", but the correct format according to the styleguide on nowiki is "4. desember 1930".
It could perhaps be the old problem with the macrocode "no" vs the actuel language code "nb".
The same problem was reported for svwiki at https://www.wikidata.org/wiki/Wikidata:Contact_the_development_team#The_use_of_.23Property:_in_time-datatype_in_Client and lawiki at https://www.wikidata.org/wiki/Wikidata:Administrators%27_noticeboard#Automatic_traslation_in_Latin so it doesn't seem to be because of the language code.
I used git bisect to find that this bug was introduced in https://gerrit.wikimedia.org/r/243640 and affects all non-English languages. More specifically, the formatter's lang option was set to a hard coded "en" in https://gerrit.wikimedia.org/r/#/c/243640/4/lib/includes/formatters/OutputFormatSnakFormatterFactory.php for an unknown reason. This suppresses a later default, set in OutputFormatValueFormatterFactory::applyLanguageDefaults. I can remove this default with no test failing.
Patches for review: