Hey, author here - great to see this posted on HN again. Let me know if you have any questions.
I notice comments that the approach is not working for various setups. I recommend starting with the most simple test - using Keytap [0] and training it with just 2 keys (for example 'q' and 'p' on QWERTY keyboard). You should get nearly 100% recall rate with "Average CC" above 0.80 for each of the 2 keys. If this is not the case, then Keytap will most certainly not work for your setup.