I totally agree with everything you stated. I was soooo excited about Shadowfever; and I almost pulled my hair out waiting on the release date. After reading it, I somehow felt let down. Everyone else was so excited and singing praises, so I read it again, but I still felt let down. I still have so many unanswered questions. Who is Barrons and his peeps? Your correlation between Barrons and the souls is interesting.
However, I was excited to learn, after releasing the Dani O'Malley triology, KMM will release more stories about MAC and the original characters. Hopefully then we will get all our questions answered.