There are fundamental linguistic challenges to actual real time challenges. Take this German sentence from an article in Der Spiegel:

In den aktuellen Gesprächen werde es darum gehen müssen, die Notwendigkeit eines von der Regierung in Gänze getragenen wirtschaftspolitischen Konzeptes zu betonen.

google translate renders it as

The current talks will have to focus on emphasizing the need for an economic policy concept that is fully supported by the government.

In the English, “emphazing” is the 9th word. In the German, it comes from “zu betonen“, right at the end. You could not construct the full English translation until you had the full German sentence, right to the end. Fundamentally the structure of the languages are different in this way. This means the best you can hope for with on the fly translation is for a sentence to be translated after it is fully complete.