I have to type Chinese as well, adding an input system switching key (or a key for "Setting") is necessary since Chinese input is not yet developed.
Globe Key for Android
Need I say more? We need a globe key for android to change to other keyboard apps, especially important for users who write in other writing systems (e. g. Asian and any right-to-left language). (And it should be accessible by long-press of the 123-emoji button, but mainly, we need a globe key.) On the app called "Google Pinyin Input", the keyboard app switcher is accessed through long-press of the space bar. This is simple, but genius imho.