[tasogare]

> but in written form, at least without colloquialisms, they are basically the same language.

No they're not. Time to go studying linguistic before writing false statements on the internet. Even if most characters and words are shared in-between Sinitic languages, there are difference in lexicon, grammar, syntax and other subtle grammatical phenomena. Phonology is also distinct. It would be incredibly painful for someone the write its native language using an input method made for another language.