You get your non-deterministic process (hired humans or LLMs) to create deterministic scripts (='generators' in EDA terms), which can then be audited, corrected, etc.

DRC/LVS/PEX/SPICE are deterministic, but the tools themselves are not without faults.

Physical design (what this seems to be targeting) already uses non-deterministic algorithms because floorplanning, placement, and routing are all difficult problems to solve with a deterministic algorithm. Introducing probabalistic approaches helps to find the right fit within the constraints.