Great question, @dbashamjr. Are you referring to a change in the Privacy Central report that has been our go-to for the past year for Amazon order reporting? If not, as @cculber2 suggests, can you share a link on the data source?
The Import CSV Line Items is pretty fussy about the way the data is organized. If the CSV doesn’t look EXACTLY like it expects, it throws up its hands and says the source file is unrecognized. So, I’m not totally surprised that you aren’t able to map the JSON to a recognizable CSV. I don’t think this approach is going to be worth the trouble.
Amazon keeps changing their reporting output. If this is a stable-ish, long-term change from Amazon and I can get my hands on sample data, I’d be willing to look at an update to the import code.
If you are in URGENT need of a solution, you might use one of your JSON-to-CSV mapping tools and try setting up your data mapping in the Simple CSV Import workflow. This workflow takes a little more setup but is more nimble and customizable to your needs.