I believe that, as of now, it is not possible to
import data into a Custom Module with an Account Look-up field
and see the custom module data on the Account immediately after import. - either through the import UI interface or via program code. I have searched the internet, spoken extensively to Zoho support but to no avail. Nowhere can I find anyone who seems to have done this.
And this isn't some esoteric operation - surely most custom modules are related items on Accounts and/or Contacts ? Without the ability to import custom module data that links automatically, the only other option is to go into each record and select the Account from the picklist, record-by-record.
So if you have, say, a Licence Agreement module and you want to see Licence Agreements listed under each Account, you'd think that all that would be necessary would be to include the Zoho Account ID in the .csv import file. But not so - if you do this the Account field on the Licence Agreement is empty. How about importing the Account Name ? No, this doesn't work either.
I'd love to be proved wrong in what I say and, if so, I'll post an apology immediately - but I fear this facility simply does not work at the moment and I think this is a major shortcoming in an otherwise excellent product.