Palettes in region files also use the shorthand (although when serialized, mixed string-compound lists are forced to use the single-entry empty-key compound structure).
I’m not sure I totally understand the issue but is the single-entry empty-key structure intended? That feels to me like it makes parsing region files more complicated. Here are block states palettes from 2 different y-level sections in the same chunk. One palette has the empty key structure while another does not. Why not be consistent? And why have empty keys?
Cool. Thanks for clarifying. I will update my parser.