Thing is that GLM 5.3 is many multiples the cost to run, and slower.

I have good results with DS4.1 flash because I can iterate faster. I either provide it with correction, or it discovers its failures via the harness. And seems to respond well to empirical evidence rather than go in circles.

So it might need some prodding, but it's likely in this case it was able to brute force after several runs and collecting some evidence.