Simultaneous translation is something that is done by good professional interpreters ... many of them work at the UN for example!
When I was travelling in the USSR many years ago, we had an interpreter with us who could do this between Russian and English in highly technical settings. He would get the intonation and meaning right (except for some obscure technical terms - which meant he said them in English when we were speaking), but did not do the hand gestures ... probably because he did not know us well.
Z