Current behavior:
Cells in Excel which have a custom format (for example a custom date), are imported into the job in their code/epoch format, whereas cells with format = Date are not imported. 

Available workaround:
Hide cells with custom format in the Excel file so they are not imported.

Requested behavior:
Make it possible to recognize cells with custom formats and not import them in the job. 

Use case:
This would avoid issues where custom epoch date codes are changed in target/don't correctly work in the completed file.