You can also use the system file to specify the extdata retrieval behavior - meaning which extdata fields should be automatically retrieved from which entity. We have tried to automatically compile a retrieval definition based on the comments in your excel sheets - see extdata_retrieve.json.
The format is pretty simple - you just specify an object for the key "extdataretrieve" and use the entity identifier (e.g. "transactions.billing") to add a list of extdata field IDs. For instance:
"extdataretrieve": { "transactions.billing": [ "axikon_vat_code", "axikon_brand_name", "axikon_sales_lang", ... ] }
