Some of these decision problems have thousands of examples because they correspond to industrially relevant problems. So, not automatically generated all at once, but gleaned from people who have been using CAS for decades to solve specific problems.

Still, I fear, the numbers are currently too small to get past the information bottleneck (mere thousands). We'll see.

Are these gathered in one place anywhere? I and probably many others, including the authors of this paper, would be interested in these as a test set for models like this.