As a developer, it is currently impossible to upload multiple sound files at once to the website. or through the Game window in Studio.
I recently got done learning how to program in AutoIt, which is a freeware automation language. I did this because I had to upload 200+ sounds to Roblox for one of my games, and I definitely wasn’t going to do it one-by-one. So I programmed my computer to do it for me.
In the end I learned a useful skill that I shouldn’t have needed in the first place.