Currently the bkr group-create command is using the XMLRPC groups.create method. It would be nice to port it to use the newer JSON APIs for groups, for better error reporting and for consistency with the web UI which is already using those APIs.
Verified by inserting logging code into both the XMLRPC and JSON handlers to watch what codepath was hit. Confirmed that the JSON codepath was called.
Beaker 25.0 has been released.
Release notes are available upstream: https://beaker-project.org/docs/whats-new/release-25.html