How to change the language for Xfce in a docker container, including the title and menu bar?

I installed the Xfce4 DE and change it to simplified chinese in my server instance (it seems a docker container without systemd) using the following commands.

apt install -y xubuntu-core xfce4-goodies
apt install -y language-pack-gnome-zh-hans task-chinese-s-desktop
update-locale LANG=zh_CN.UTF-8 LANGUAGE=zh_CN LC_ALL=zh_CN.UTF-8

However, the things didn’t turn out the way I excepted, some text keep English.

the image is here

I noticed that these three environment variables have the above values in terminal emulator.

I’ve attempted to execute dpkg-reconfigure locales or add the following contents to ~/.xprofile and ~/.profile. It still not changed.

export LANG=zh_CN.UTF-8
export LANGUAGE=zh_CN
export LC_ALL=zh_CN.UTF-8

I even changed the other language like fr-FR and install the corresponding packages above, it have the same issue.

Did I missed something?