I think it's wonderful that you adopted this little one. As for the barking - when I brought my Lexi home, (I had 2 older Shih Tzu) she played very little & just wanted to sit in my lap & "observe". She never made a sound for 3 days. Believe me, she has made up for it since then.
I think you will find out soon if yours can "talk" or not. I have seen dogs that have had surgery to prevent barking, but they still made some sounds - reminded me of when someone has laryngitis. Hoping this had not happened to your furbaby.