It is my understanding that dialects in China very all over the place, far exceeding, for example, the difference between someone from Brooklyn and someone from the deep South both (attempting) speaking english, and that it is not all that rare for two Chinese from different parts of the country to have difficulty understanding each other. This is due not just to differences in vocabulary (as in the difference between common English and Ebonics), but in significant differences in pronunciation, inflection, and tonality (as in the difference between American English, English English, and Scotch and Irish English). There are very few English movies I can understand without the subtitles. In the case of Chinese, I understand that these strong dialectic differences are enforced, or at least facilitated by the pictographic nature of written Chinese which gives no hint as to pronunciation.
As far as the forming of plurals, there are many instances of two languages having the same word in the singular, such as 'television' in English and Spanish, but differently spelt and pronounct words in the plural, e. g., 'televisions' in English and 'televisiones' in Spanish. Both versions are correct in their own language even if one is derived from the other as in this case. (And I notice that my spell checker rejects the Spanish version.) So, I shall always write 'forums' rather than 'fora' which strikes me as a typo of something that should go with 'flauna'.
There is an overarching rule that applies: Language is a tool to be used for most clarity, not a doctrine to be followed with greatest piety.
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