The concept of end to end encryption (E2EE) is sometimes used as a marketing gimmick. True E2EE is possible only if there is a direct connection between users computers. If a system has a server, it cannot be called truly E2EE but there are other mechanisms to provide security.
In our system for audio and video the connection between 2-3 interpreters of the same booth is direct. So audio and video are end to end encrypted.
If there is more than 3 interpreters in the booth, audio and video travel through our server which means that they have to be momentarily decrypted and then encrypted. However our servers are secure and adhere to the best practices.
Your text chat messages are encrypted in transfer and on the server.
We are working on a technical solution to make the entire system truly E2EE.