Yup, I understand the problem space. I wrote one of the ports for zxcvbn and have been maintaining it for the past ~7 years. You are absolutely right there, an

Yup, I understand the problem space. I wrote one of the ports for zxcvbn and have been maintaining it for the past ~7 years. You are absolutely right there, and zxcvbn makes a guess by using the whole character set for a specific type. It groups a whole bunch of special characters together as well, potentially overestimating passwords that contain a special chars. This is mitigated by the fact that it's much less important to be good at estimating the score of a properly random password than it is at estimating poorly (human) constructed password. It's a game of making the best assumptions you can, but total accuracy is not something to shoot for here.