To localize a text in a js file (like static/js/main.js) :

• pass your text as an argument to function i18n.gettext() (for examples, see in static/js/main.js), actually your text must be in Esperanto. Use DeepL to translate from English to Esperanto if you don't know Esperanto.
• run make in motioneye directory
• edit the .js.po files for languages you are able to translate, they are named locale/*/LC_MESSAGES/motioneye.js.po. You can edit them with a text editor, or with dedicated software like Poedit or Virtaal.
• rerun make to take your translation changes into account