Anyone has experience, tips or pointers on converting and loading large-ish scale legacy data into Wikibase? Is there no complete solution (envisaged) for this right now?
Even though this topic is a few days old, I would like to add some of my experiences. I had the same problem about a year ago and wrote a Java program to insert millions of items pretty fast. It works for the LTS version. I don't know if it also works with the current version.
You can find the code here: https://github.com/jze/wikibase-insert
Best wishes, Jesper