Source: https://yanqiyu.info/2020/08/30/fcitx5-fedora/
sudo dnf install -y fcitx5 kcm-fcitx5 fcitx5-chinese-addons fcitx5-table-extra fcitx5-zhuyin
sudo alternatives --config xinputrc # choose fcitx5.
cat << EOF > ~/.config/environment.d/00-fcitx5.conf
INPUT_METHOD=fcitx5
GTK_IM_MODULE=fcitx5
QT_IM_MODULE=fcitx5
XMODIFIERS=@im=fcitx5
EOF
ln -s /usr/share/applications/org.fcitx.Fcitx5.desktop ~/.config/autostart/
sudo reboot now
好了。
Spotify still doesn't f***ing support fcitx tho.
https://community.spotify.com/t5/Desktop-Linux/Japanese-input-stopped-working-on-Linux-with-new-Spotify-update/td-p/5184677