Live translations is a difficult skill to start with, and doing them for a game is even more difficult since whoever's doing the translating needs to know a lot about the game, and in most instances about the lore, in order not to accidentally give away too much info, or mistranslate things completely. The letter where they do have live translations are often (partially) prepared beforehand and don't have any surprise questions.
Considering the upcoming one is mostly about the CE, and not about actual game content, I guess they could've done a live translation, but then people will start to expect live translations for every live letter :)
