Has anyone managed to get Seedbed running for end-to-end testing?

I managed to update the Dockerfile and scripts to build successfully using the bullseye node package and bellsoft-java8, however I'm stuck with the yarn.lock looking for the seedbed package on cache.sugardev.team.

I looked around and it doesn't look like that package is available anywhere else, so I'm not sure if I should just abandon this effort?  We were really hoping to re-use a lot of the generic step-definitions the Sugar team had built.