You're right — my map does not necessarily represent the underlying semantic structure of Australian law, it is an approximation, one that is biased by the data I used (which as I mentioned, is missing laws and cases from a number of jurisdictions), the embedding model I selected and the dimensionality reduction model I used to project my embeddings into a two-dimensional space, to name a few.
Because I was writing for both legal and data science audiences, I tried to avoid sounding like my inferences are anything more than just inferences but without getting too technical and explaining the inherent limitations of any attempt to semantically map knowledge with today's technology.
I will just say though that, having studied law myself, Australian case law is indeed somewhat of a continuum. A single case may touch on many areas of law and there are no restrictions in terms of subject matter on what precedents a judge may draw upon in reaching a decision, apart from that they are both relevant and binding (or, if they are not binding, are not treated as such).
It was also interesting to observe how the final clusters that developed were uncannily similar to the way in which I was taught law at university. It goes to show, there's a lot of thought put into the design of our legal courses here in Australia. In fact, there are 11 subjects that are mandatory, known as the Priestley 11: https://en.wikipedia.org/wiki/Priestley_11. All of those are reflected on the map, although some have been rolled up into larger categories or divided by other means.