For Australia / New Zealand we allow both answers for multiple reasons of debate including which is more southerly and whether or not English is a dejure language.
It wouldn't work with the way the planet is shaped, because there is no such a thing as an "absolute" East or West (while there is an absolute North and South).
Chinese is a bad example... Languages of China are very different and it's in fact wrong to consider them dialects of Han Chinese. "Chinese dialects" is a term used by the CCP to enforce their standard language policy.
Serbo-Croatian isn't a "language" either, following your logic. However, it's undeniable that Serbian, Croatian etc. are just dialects of one language. The same applies for Hindustani and its components (Hindi and Urdu). The difference is political and religious.
I had absolutely zero clue about Hindustani, but i thought it sounded like one of those native languages from one of the South Pacific islands and got it second try with 15 seconds leaft
Not as of this featured quiz. As per the quote from the Constitution: "The state language of Tajikistan shall be Tajik. Russian shall be the language of international communication." The state language of Tajikistan, which I understand to be synonymous with official national language, is Tajik, and only Tajik.
English is the official language of New Zealand together with Maori. But it doesn't mean, that English is not official, they just have more languages, just like many other countries. And New Zealand is definitely more to the south if we only include integral and inhabited regions. The only part of Australia, which is further south than New Zealand, is the small uninhabited Macquarie Island.
https://en.wikipedia.org/wiki/List_of_countries_by_southernmost_point
Also what does Fiji have to do with French? 🤔