I was chatting with one of my professional opera singer friends yesterday. I told him what the reviewers said and asked him if he had any idea what the whole "locked registration" thing means. He said it was very vague and therefore, in his opinion, not very helpful. He suggested that perhaps it means she thought I was using my throat to make some of the notes? He was so cute because he became not exactly outraged but annoyed on my behalf because of the vagueness of the comments from that particular reviewer. Regarding the head/neck out of alignment thing, he suggested that I… yes… sing in front of the mirror to see what my head is doing. He reminded me that it's all about the breath, and that once you get that down, you can sing in any position.
So what it comes down to is… as much as I dislike it… I will go to the mirror… and sing.