wgAdd/RemoveGroups has:
'+guwiki' => [ 'sysop' => [ 'autopatrolled', 'rollback', 'transwiki' ], // T119787, T119787, T120346 ],
however https://gu.wikipedia.org/wiki/Special:ListGroupRights#sysop isn't displaying that and indeed local sysops are unable to add/remove the group.
This is incorrect as the group is called 'rollbacker' not 'rollback'.