I would imagine they'd be stupid if they did use AI. I've seen people use AI to "write" technical documentation that I have had to review. That shit goes straight into the bin because the time I spend fixing all the AI nonsense is about the same amount of time it would take for me to write the document myself. It's gotten to a point where I straight up reject all AI generated documentation because I know fixing them is a waste of time.
I imagine legal documents have to be at least as precise as technical documents, so if they're checking the output I seriously doubt they're saving any time or money by using AI.
Interestingly that's the exact thing I loved about Hollow Knight. I got so immersed in the exploration specifically because I got lost. On my first playthrough I ended up sequence breaking the game and cleared out deepnest, ancient basin, hive and kingdoms end before the city of tears. I was way out of my depth and I loved every moment of it.