Managed to get Chinese input on KDE Neon using fcitx. These are the packages I have installed:
sudo apt install fcitx fcitx-bin fcitx-config-common fcitx-config-gtk fcitx-data fcitx-frontend-all fcitx-frontend-gtk2 fcitx-frontend-gtk3 fcitx-frontend-qt4 fcitx-frontend-qt5 fcitx-module-dbus fcitx-module-kimpanel fcitx-module-lua fcitx-module-x11 fcitx-modules fcitx-ui-classic im-config libfcitx-core0 libfcitx-gclient0 libfcitx-qt5-1 libgeoclue0 libgettextpo0 libjavascriptcoregtk-4.0-18 libpresage-data libpresage1v5 libtinyxml2.6.2v5 libwebkit2gtk-4.0-37 libwebkit2gtk-4.0-37-gtk2 presage zenity zenity-common fcitx-libpinyinTo start at login:
sudo cp /usr/share/fcitx/xdg/autostart/fcitx-autostart.desktop /etc/xdg/autostart/I was having an issue where the fcitx configurator window would pop up at login, which I did not want. I edited the Exec= line as shown, which seems to have alleviated the problem:
...
#Exec=fcitx-autostart
Exec=fcitx
...Not sure why fcitx-autostart also opens fcitx-configtool at login. If I close everything and run fcitx-autostart from xterm, it does start the little systray applet thing, but not the configurator. From what I can tell, it only opens the configurator when it runs at login.