>>>sagovornik - go-between
>>
>>Nope, that's the "potrcko" (the runabout, literally) or "posrednik" (middleman). Sagovornik is interlocutor in English - but nobody uses that word; I haven't heard it ever, just found it when I was checking. Sa=with, govoriti=speak, so, co-speaker, partner in conversation. Two people who talk are sagovornik to each other.
>
>Go-between is also an interlocutor. How about "Arbiter"?` (the interlocutor in a dispute)

The person you're talking with, nothing more nor less. Just talking, literally, with-speaker (yep, govornik means speaker, orator).