ScriptRunner for Bitbucket currently has partial support for Atlassian's Data Center Migration Tool.
ScriptRunner for Bitbucket supports the migration of project and repository administrator configurations including Pre Hooks, Post Hooks, Merge Checks, and Listeners.
However, any hardcoded project, repository, or user IDs existing inside custom scripts need to be manually updated by the script author following migration because the ID referenced may no longer be valid or point to a different entity in the import instance.
Atlassian's migration tool is designed for the migration of individual repositories and/or projects. Handling the migration of globally applicable configurations is not well suited to the tool and the use cases it is designed for.
We have opted to not include support for migration of global configurations at this time.