Hi Diego Poggioli ,
Welcome to Microsoft Q&A platform and thanks for posting your query here.
As per my understanding you want to know if there is a way to redefine the column order in custom connector in Microsoft Purview.
You can try "Column Mapping" where you can define the source and sink in json and define the column orders as an array of individual objects.
For more details, kindly watch out the following video: Azure Purview Column Mapping
Hope it helps. Thankyou.