Bugs found while using the Twine 2.x application should be reported on the Issues page of the application's repository, because there is no guaranty that the Twine 2 developers will see a question on this Q.A site.
Any suggestions on how to improve or extend the the functionality of the Twine 2 application should be made on the same Issues page, but please use a separate Issue to the one that reports a bug as this helps the developers track bugs & enhancements separately.
RE: Recovering a particular version of a story project.
Did you use the Publish to File option to create a story HTML file based on the latest version of your project?
Did you use the Archive option to backup your story projects before you did the 'import' that corrupted your later version project?
If the answer to either of the above is Yes, then you could possible use either of the above HTML files to recover the later version of your project.
I strongly suggest using the Archive option to make regular backups of your projects, and to especially use it before any process (like importing) that effects the contents of one or more projects.