My first approach is to look for references to the project on GitHub. Since this project is not itself on GitHub, next best option is to search the URL for code comments, docs, etc.

https://github.com/search?type=code&q=web.mit.edu%2Fmatriarc...

It has one result, which appears to be someone demonstrating their visualization library using a model from Matriarch as an example.

Would love to hear from users of the software.