try {
var sales_order_id = salesOrder.save({

ignoreMandatoryFields: true

});
log.debug(‘record save with id’, sales_order_id);//sales order internal id
// load customer record
var customer = record.load({
type: record.Type.CUSTOMER,
id: salesOrder.getValue('entity'),
isDynamic: false
});
customer.setValue({ fieldId: 'myfield', value: 'my new value'});
var customerId = customer.save();
return id;
} catch (e) {

return 0;
}

The above modification to the existing example code will load the customer record from the Sales order after you’ve saved the sales order.  As a side note: I would recommend that likely a more “appropriate” place for the code where you want to change a value on the customer record after saving the sales order would be to use the afterSubmit function of a UserEvent script on the SalesOrder record type itself.

Also, if you already know the value and field(s) that you want to set on the customer record, it’s going to be more efficient to use record.submitFields function rather than loading the customer record/setting values/saving customer record as I show above.

using record.submitFields, replace the above code with the below code:

record.submitFields({
type: record.Type.CUSTOMER,
id: salesOrder.getValue('entity'),
values: { my_field_id1: my_new_value1, my_field2: my_new_value2 },
options: {
        enableSourcing: false,
        ignoreMandatoryFields: true
    }
});

Sorry I was late to the party but I hope you find this useful.