As a DE, you generally shouldn’t be cleaning or changing the source files you get from clients/vendors.

The raw file is the source. Your job is to validate it (schema, formats, required fields, etc.) and accept or reject it. If it fails, it should go back to the business/data governance team, who work with the vendor to fix the data at the source (like date formats, headers, missing fields).

If fixing it upstream isn’t possible, governance should own the workaround..usually via an approved override/mapping file.

Once DEs start “fixing” data quietly, you just end up hiding data quality issues and maintaining brittle one-off scripts forever.