I'm wondering if invoice_transaction_summaries and order_transaction_summaries are actually needed?
For example, order_transaction_summary.json contains only a numTransactions property. Can you just query the transactions live to get the count? I guess maybe the fact that it says "expected" means that the transactions don't yet exist?
If the answer is no, can you add the normal CRUD APIs for managing these tables?
If you look at https://s3.amazonaws.com/foliodocs/api/mod-finance/p/transaction-summary.html you can see the API only support POST and PUT, but not GET or DELETE.
You need both of those when migrating data. When working on migrations, you need the ability to clear the tables.