Is there any way to customize the CSV Import process through SuiteScript? E.g. I have a CSV with different columns then my custom record and I need to adjust them via code?

CSV Imports will fire User Events if configured to do so. There's a setting in the CSV Import Advanced Options page to trigger server-side scripts and workflows.

hmm but that will still not work if I have for example 10 columns in the CSV but want to map that to 5 columns in the custom record as it would be AFTER the line was already processed and the user had to select the mapping correct?

I must be missing something. What exactly is not covered by the mapping stage? CSV Imports will trigger User Events, and thus you can hook up a

beforeSubmit

, so the line won't have finished yet.

There is no way to modify the saved csv import mapping via code as far as I know

But I still need to map each CSV column to a column in my custom record. But in my case that is not possible. Based on looking through documentation I think @rustyshackles is correct