In general, the task from the table to create a contact in Google, but in the official manual ( https://developers.google.com/apps-script/reference/contacts/ ) did not find a method for adding or editing the middle name field, additional Name. Prompt, it is generally possible within the framework of the script. that's what I have already written:
function addCont(contact,G1,G2) { var cont = ContactsApp.createContact(contact.NAME[1], contact.NAME[0], contact.MAIL); cont.addToGroup(G1); cont.addToGroup(G2); cont.addCompany(contact.KORP,""); if (contact.KORP==contact.NAME[0]){ contact.KORP = ""; }else{ contact.KORP = " (" + contact.KORP + ")"; cont.setSuffix(contact.KORP.replace(" (","(")); } cont.setFullName(contact.NAME[1] + " " + contact.NAME[2] + " " + contact.NAME[0] + contact.KORP); cont.addPhone(ContactsApp.Field.MOBILE_PHONE, contact.PHON); } if use
cont.addCustomField("Additional Name", contact.NAME[2]); then he makes a separate entry in the custom field, and less is needed for him to enter data into the variable intended for this, it is provided by Google contacts, 
but how to make a record there, until I found it, otherwise the phone displays the contact is not correct.