Apologies, no, I don't know at all. All I know is that the problem to solve is the same and I don't know how it's done, and assumed it would be code along the same lines. I don't have anything like the 1.12 code specifically referencing models inside the later version code. It just seems finds the right model as if by magic, and I don't know how it is doing it, unless its the text match between block and json names. My code is largely cut-and-paste from tutorials and examples, and then edited to what I need, and I'm looking for some basic help on how to make this next edit.
For 1.