So, here we get to the fundamental issue then: Chinese seems to have a larger divergence between spoken and written register than most other languages (particularly alphabetically written ones).

It's unclear to me how far that extends. (This issue seems intertwined with the issue that many speakers of other Chinese "dialects"/"languages" also use Standard Written Chinese (ie Mandarin), btw.)

It is possible to write some register of Chinese in phonetic writing, though - that's shown by Dungan (written in Cyrillic), by the experiments in the 30s (quoting Mao again: "we have begun experimenting with Hsin Wen Tzu—Latinized Chinese. It is now used in our Party school, in the Red Academy, in the Red Army, and in a special section of the Red China Daily News."), etc.