I've written my own autoplacer/autorouter. Placement is where you put the components on the board, routing is how you shape the traces to interconnect them.

It does a pretty decent job on small hobby-project boards of ~40 components (which is my use case at the moment), and I'm working part-time in the background on scaling it further.

The resulting designs pass all the KiCad electrical and geometry checks. Granted, I've spent about a year working on this problem, and it's hard, but not that hard a problem, providing you can avoid falling off the exponential cliff by decomposing it into hierarchical subproblems.

Quick-and-dirty unsupervised whole-board synthesis from schematic takes about 5 minutes, longer if you want cleaner output with nicer-looking better-routed traces.

As others here have said, placing is the real problem to solve, and that's where the magic happens. Place the components right, and routing is a relatively easy loosely-coupled constraint programming problem, place them wrongly, and you will have to get used to seeing the word UNFEASIBLE in your log output.

This project sounds very cool. Is it open source? If yes, can you share a link to the repo?