Pass event date and event name as custom fields to Infusionsoft. From https://eventespresso.com/topic/infusionsoft-bring-in-the-event-name-into-a-custom-field/

plugin.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

function ee_infusionsoft_pass_event_start_and_name( $is_contact_data, $ee_attendee ) {
    if( $ee_attendee instanceof EE_Attendee ) {
    $startdate = '';
    $eventname = '';
    $checkout = EE_Registry::instance()->SSN->checkout();
        if ( $checkout instanceof EE_Checkout ) {
            $transaction = $checkout->transaction;
            if ( $transaction instanceof EE_Transaction ) {
               foreach ( $transaction->registrations() as $registration ) {
                    if ( $registration instanceof EE_Registration ) {
                        $event = $registration->event();
                        if ( $event instanceof EE_Event ) {
                            //get the event start date
                            $startdate = date( EED_Infusionsoft::IS_datetime_format, $event->primary_datetime()->get_raw( 'DTT_EVT_start' ) );
                            //get the event name
                            $eventname = $event->name();
                            $is_contact_data[ '_yourISfieldfordate' ] = $startdate;
                            $is_contact_data[ '_yourISfieldforeventname' ] = $eventname;
                        }
                    }
                }
            }
        }
    } else {
        EE_Error::add_error(sprintf( __( 'ee_infusionsoft_save_my_custom_questions was not called with an EE_Attendee but a %s', 'event_espresso' ), gettype( $ee_attendee )), __FILE__, __FUNCTION__, __LINE__ );
    }
    return $is_contact_data;
}
add_filter( 'FHEE__EED_Infusionsoft__save_infusionsoft_attendee__extra_attendee_data', 'ee_infusionsoft_pass_event_start_and_name', 10, 2 );