Creates an English post, and attaches a Russian translation to English post programatically. Thanks janekS!

wpml_translate_create_translate_post_programatically

function multilingual_post_creation(){
 
global $sitepress;
/**
        /**
        Creating first post in english
        */
 
        //arguments for post creation
        $def_args = array(
            'post_title'    => '[en]Test post - ' . date("d.m - H:i:s"),
            'post_content'  => 'Text in default language goes here',
            'post_status'   => 'publish',
            'post_type'     => 'post'
 
        );
        //creating post with arguments above and assign post id to $def_post_id
        $def_post_id = wp_insert_post($def_args);
        $def_trid = $sitepress->get_element_trid($def_post_id);
 
        /**
        Creating translation of first post in another language. Right now for russian
        */
 
        //arguments for post creation
        $ru_args = array(
            'post_title'    => '[ru]Test post - ' . date("d.m - H:i:s"),
            'post_content'  => 'Text in russian language goes here',
            'post_status'   => 'publish',
            'post_type'     => 'post'
 
        );
        //creating post with arguments above and assign post id to $ru_post_id
        $ru_post_id = wp_insert_post($ru_args);
 
        //change language and trid of second post to match russian and default post trid
        $sitepress->set_element_language_details($ru_post_id, 'post_post', $def_trid, 'ru');
 
}