How to send selected language from frontend UI to backend Jigasi

Right now English subtitle in Jigasi is working fine. Now I want to give language selection options to participants. Participants can select any language among Us-English, Bangla, Hindi, and Urdu. But how to connect fronted UI and backend Jigasi. So that when language is selected the backend jigasi will send that language code to google.

This is available in latest unstable packages and will soon hit stable. jitsi-meet/config.js at 9e11bc302b61e09f0e646f50d00355c7324cfa6f · jitsi/jitsi-meet · GitHub

Actually, I am talking about transcription, not translation.