I'm genuinely surprised by how awful the resulting PCB is. A trivial LED matrix like this is pretty much the best-case scenario for tooling like this. Not being able to handle this is a pretty damning - although a decent bunch of the blame should probably be placed on whatever third-party autorouter they are calling out to.
Even with better results, the big issue with tools like these is that they simply don't match with the kind of development style that's needed for the problems at hand. You see the same issue with those drag-and-drop visual programming languages, or scripted modeling like OpenSCAD: they end up making fairly trivial details slightly easier, while significantly complicating the meat-and-potatoes. Nobody cares about a neat little part placement for-loop if it generates a living hell of autorouted spaghetti you can't possibly interpret and fix manually.
In reality the low-hanging fruit has already been covered by existing tooling. Automatically generating symbols and footprints from textual descriptions is routine practice, and software like KiCad already has a reasonably usable scripting API and a well-documented file format. A lack of code-based code-based EDA hasn't stopped projects like Ergogen[0] from popping up. The main limitation for additional automation is a lack of reliable input data, and user-side tooling can't fix that.
(tscircuit maintainer here) It might be easier to think of tscircuit as an electronics CAD kernel. We're MIT licensed and web-compatible, so we would make a great foundation for people building new EDA tools or people who would like to generate electronics (think domain-specific tools, e.g. a website that allows you to quickly build a custom keyboard)
FWIW In this case I think this board called out to freerouting for the routing. Companies have reached out to us with autorouting APIs, so we'll support different vendors and hopefully allow enough constraint-specification for people to get good results. Autorouting is important for reusability, even if it's routing between manually-routed sections (e.g. fanouts)