If you are going to do a Live Letter

[Fawkes]

Didn't say so in the news. Neither in english, nor german news.
That's like announcing content updates and the content is japanese only.

They could do it in english or as others do, do a live translation over the streamed content via translator who is not with them on the booth, but exclusive for the stream.

That would be expensive, complicated, and completely unnecessary. This stream had five people speaking Japanese to each other. So, you want them to hire five translators to listen and translate at the same time and hire more engineers to run a separate stream with balanced audio so you can hear the translators over the people they're translating but also still be able to hear when they play a music clip (which Yoko Taro also talked over, so you'd need the translator talking over that and end up not hearing the music or hearing too much cross talk with Yoko Taro and the translator)