We are in the process of building those scripts. As we are working with companies for migration we started to improve these scripts to cover more edge cases. These should be out sometime soon.
Otherwise, we have a public API to do CRUD operations for all important entities (issues, labels etc). We are working to get an openAPI spec once that is out we should have all the APIs added to our https://docs.tegon.ai
If you have an API to manage issues, that could work as well. Would need that anyway for custom build integration etc.