The most important elements of the Biquad Cookbook repo - the filter fomulas, explanations, references to source material, Excel spreadsheet, and plaintext cookbook - were all created by hand.
This web-based EQ designer was mostly vibe coded, with manual corrections to some of the labels, default values, calculations, etc. I don't enjoy working on web-based projects, but if you do then human contributions are welcome. If you find a bug or have a feature request for the EQ designer then please open an issue, but if you ask me to work on a web page expect it to be slop.