No. I doubt if many people would understand the first two, either.Would there be other synonyms to these words? Would the noun "co-talker" do?
I suppose that if you were giving a lecture, you might refer to other speakers as your co-speakers.Would such words as "co-speaker'' or "co-talker" exist in English?
I had not heard the word before I became an UCLES examiner.The only times I have seen these words used is in exam descriptions.