This function allow to translate (query translated objects) your ACF relationship fields

ACF_WPML_translate_relationship.php

<?php
/**************************************************************************************************
 *
 * ACF / WPML translate relationship fields
 *
 *************************************************************************************************/
add_filter( 'wpml_duplicate_generic_string', 'my_override_post_duplication', 10, 3 );
function my_override_post_duplication( $value_to_filter, $target_language, $meta_data ) {

	if ( isset($_POST['icl_ajx_action']) && $_POST['icl_ajx_action'] == "make_duplicates"){

		if ( $meta_data[ 'context' ] == "custom_field" && $value_to_filter !== '' && $meta_data[ 'key' ][0] !== '_') {

			$field = get_field_object($meta_data[ 'key' ], $meta_data[ 'master_post_id' ]);
			if ( $field['type'] == 'relationship' && $meta_data[ 'attribute' ] == 'value' ) {

				if ( $meta_data[ 'is_serialized' ]  ) {
					$values = unserialize($value_to_filter);
					$new_values = array();
					foreach ($values as $value){
						$post_type = get_post($value)->post_type;
						$new_values[] = apply_filters( 'wpml_object_id', intval( $value ), $post_type, false, $target_language );
					}
					$value_to_filter = serialize($new_values);
				}
			}
		}
	}

	return $value_to_filter;
}?>