This site said that Japanese is the original language, so I added the Japanese voice actors: https://www.starwars.com/news/star-wars-visions-trailer-and-cast

The new trailer — available in both the original Japanese and translated into English — provides a glimpse of the captivating tone and stunning visuals from each of the nine animated shorts, which can all be viewed both with the original Japanese voice cast or the English dub cast when the series launches on Disney+ on September 22.

Also, the official Star Wars YouTube channel callled the Japanese trailer the original trailer: https://www.youtube.com/watch?v=lle0NNmvIyU