Hi Justus,
I know it’s possible to import an excel document and map certain rows or columns to entities.
Check out some of these links, and met me know if this solves your issues?
https://docs.mendix.com/howto/integration/importing-excel-documents
https://docs.mendix.com/appstore/modules/excel-importer
https://docs.mendix.com/howto6/importing-excel-documents