But this experiment didn't lead to a marked improvement on the way to superintelligence, now did it? A set of LLMs, set up to this tasks by humans, managed to create a smaller LLM that is just as much a transformer based sequence predictor, with the same basic flaws.

That isn't self-improvement in the sense the explosive self-improvement of a superintelligent AGI is described.

That is painting a car a new color. It's a new color coating, it may look very good, and the effect may be desirable and useful. But it's still a car, and no closer to a warp capable spaceship than before.