I've edited controller_input.rpy to allow players to type in Simplified Chinese using a pinyin keyboard.
Download the files from the link below:
https://mega.nz/folder/KUBjXAIA#d7axn9Aj8ZwthpTl4g-LnA
and place the files in backend/controller_support.
Now, calling universal_input allows you to type in Chinese.
You'll need to credit Yan-Gyan or 羊圈Yan-Gyan for using this patch.