There's a little typo--it's actually 4.1.1 that refers to consistency. And if it might provide any further support to you and your student, this is interpreted to refer to consistency of structure, in context with the rest of that guideline. This means that once you have figured out the book, centered headings, cell-5 headings and so forth will be designated in braille in a consistent manner. It does not particularly refer to balancing centered headings. As you rightly suggest, that old rule about the chapter number on a line by itself is gone, gone, gone!
I'm very glad to have been of any help.