Aside from the issue of a few duplicates in different categories, I largely concur with all of this.
I reckon being relaxed about duplication is the key to getting a sensible-looking set of cascade skills. There's a lot of overlap between Social Science and humanities, but that's quite deliberate. Many disciplines, such as archaeology, have a wide range of approaches and techniques, with some practitioners coming at it from a humanities background and some from a more scientific background. This is the basis of many academic turf wars.
It was actually something I raised in play test - at the time there was just one Science skill, and everything was branched underneath as Specialities. I thought it was unrealistic that somebody who studied, say, History was automatically connected with the basics of Chemistry for example. The broke it down to the four categories in the final release, but I wasn't ever really satisfied with Social Science and Space Science still.
Social Sciences, like Psychology and Sociology are different in their approach to Humanities like Philosophy and History (basically, they attempt to be inductive and predictive in method), while I don't really see how Robotics was included as a Space Science (much better as a Mathematical or Computer Science), but Astronomy wasn't included!
I'm glad it was at least broken down into different disciplines, and thanks for raising the issue at playtest.