Great work! To make it even simpler for newer learners, it could be nice to have some text explaining that the squares indicate the actual=No/negative, and the circles indicate the actual=Yes/positive. IT could also be useful to add this information into the cursor hover labels. And maybe axis labels to clarify that x-axis="test score" or "model predicted probability" and y-axis="count" or density or whatever.

Thank you! I will implement your suggestions on occasion.