Catnip is in English, how can it be set to Chinese?

You can make a PR at https://github.com/ct-js/ct-js/ to update the translation file. The needed file with instructions is at https://github.com/ct-js/ct-js/tree/develop/app/data/i18n

Catnip was translated by Emaoshushu at Github 👏 Right now you can get translation with the Nightly version of ct.js.