IMHO hiding details of the hack helps conceal that they built it to do what it did, and maybe were able to know it was working just as intended.

The fact it keeps doing it, with more and more evidence, is a sign that it's built that way.

This is a program running on their montoroed machines that they purpose built and monitored its training at every step. I think it'd be way more suprising that they didn't know it used note taking and cross-run memory.