I imported an export of Anytype as markdown zip.
Everything turned into chaos, icons were not applied, links for some reason were not saved, although all the ticks were checked during export, most of the pages broke.
HOW TO
Import the zip that you exported from Anytype
This is not a solution but rather help to cleanup the mess 
You could create a Set with Relation Creation Date, and then filter on Objects created on the day (and time?) of the import. From that Set you should be able to batch delete Objects.
Thanks ! But there was still a bug with links and pages