I have a strange case where a UE script (afterSubmit function) works properly if the record was created manually, but gives an error on CSV Imports. I mean, what is different here?

What is the error you are getting?

The script is creating an Advanced Intercompany Journal... the error says the entity ID on the first line is incorrect, although it is the same one used when it gets triggered by doing Edit&Save.

Can you check if there duplicates for that id, CSV works with Text value ? Since it is aftersubmit, You must be able to create/update records, can you log everything you are setting before actually setting, you might get a difference there.

I tried but wasn't logging everything... will add more logs.