Wow. I worked on Millwheel as a summer intern the summer before last. At the time it was a team of about 11 people. I'm honestly pretty surprised to see this comment as I thought it was just a small internal research project.
Have you seen any references to it in the wild other than the Google Research paper?
Feature request: Could you strip the dots from user input if the email address is @gmail.com, and similarly strip the dots from the records of pwned email addresses? Gmail usernames are dot agnostic, and I sometimes use email@example.com, firstname.lastname@example.org, etc. This makes it hard to use the tool to check of my Gmail has been pwned. (Also, I assume you don't do this already).
I wrote a simple neural network about a year ago for doing optical character recognition as a class project. I think looking over the code could be good for learning, as it has a pretty simple OOP structure: https://github.com/bcuccioli/neural-ocr
There are two good correct equivalent ways to think of the determinant of varying generality. One is as the function from a ring of square matrices to the underlying field (e.g. from R^(n^2) -> R) that sends identity to identity, is alternating (swapping two rows or columns negates the function) and is multilinear (is a linear function in each of the columns independently). These properties are all useful and important on their own, so there is motivation to study a function which has all of them. It's not obvious that such a function exists, but you can prove that. As it turns out, these three properties uniquely determine such a function, which makes it seem like that function might be really important!
There's a more general definition too, which is based around the wedge product, a quintessential object in algebra and calculus. There's a good exposition here: http://codeblank.com/~int/det.pdf .
The difference is calc 1 is not higher level math and the derivative of a real function is not an abstract concept. Professional mathematicians/grad students/high level undergrads don't think of the determinant via some weird geometric intuition, as that won't really provide enough information or rigor to do anything useful.