Communication between jitsi-meet jvb jicofo and other components
There is no such document.
For the communication between jicofo and jvb there is a document which wasn’t updated from a long time: https://xmpp.org/extensions/xep-0340.html
For communication between client and jicofo you can open a conference and whenever you do
APP.conference.saveLogs() in the js console you will have a json file with all xmpp communication, it is standard xmpp and muc https://xmpp.org/extensions/xep-0045.html with just one custom iq in the beginning send to jicofo.