About UI language

[swordpp]

I created a Docker container, using parameters -e LANGS=zh_TW.
Then I opened the web interface, it displays the English interface, and i set the interface language, but the next time I open it, it still displays in English. Why?
I am using command:
docker run -d
-p 8080:8080
-v /home/s-pdf/trainingData:/usr/share/tessdata
-v /home/s-pdf/extraConfigs:/configs
-v /home/s-pdf/logs:/logs
-v /home/s-pdf/customFiles:/customFiles
-e DOCKER_ENABLE_SECURITY=false
-e INSTALL_BOOK_AND_ADVANCED_HTML_OPS=false
-e LANGS=zh_TW
--name s-pdf
frooodle/s-pdf:0.27.0-ultra-lite

[Frooodle]

LANGS to define custom font libraries to install for use for document conversions

What you want is
SYSTEM_DEFAULTLOCALE: en_US