I agree that a web-based password generator is not ideal and have mentioned this in the about page. This is mostly due to Math.random() being pseudorandom. However, the application does try to be a bit better than some of the services currently out there by seeding Math.random() and using window.crypto.getRandomValues() to generate cryptographically random values where available.
Also, it goes without saying but the passwords are generated on the client as all similar services should.
Using remotely loaded JavaScript code. This is just not safe.
That said, it's a nice UI, OP. I wouldn't abandon this because of the lack of response you got here.
[1] https://bitcoinpaperwallet.com/bitcoinpaperwallet/generate-w...
I have a GitHub project (https://github.com/cxam/passed.pw) open at the moment to track issues and plan to make this open source soon after fixing any bugs found during the initial trials.
All the libraries used in this project are open source and I have listed these on the about page with the relevant links.
I suggest re-doing this with a better stack.