I always figured Elwin was the correct spelling, but I totally understand how Erwin makes sense too. Also, in the trailer, I saw "Sulras" and other weird or bad spellings which got me worried, but then they say "Salrath" on the website, so that's good! It makes sense if the trailer was just using some very old build of the localization.
Anyway, yay! Looking forward to it.
Edit: Coincidentally, I was watching this, and at the very end it says "Sulras" so I guess that's where they got it from: https://youtu.be/ko2vHgn-b88?t=2503