With tech where it is today it’s entirely possible. Remember the HG isn’t right there on the stage with her, they are using CGI to show it there.

The audience is seeing on a screen probably on the back wall.

As for the translator, no problem. Just program the computer with your voice and the text of the speech, process it and you can then project the hologram on a screen.

The real trick will be in getting to where you can project it to any given point in a room without a screen like we see in Scifi today.

That’s going to take a while.