‘QTags.addButton: arg2 distorts the button rather than just shows

This is about adding button to Text tab in when a post is editing.
In other words, this is about Tinymice.

function _get_timeline() {  
    $script = 'QTags.addButton( id="timeline", display="Timeline", arg1="<div class="n-timeline"><p data-aos="flip-left">Текст", arg2="</p></div><!-- .n-timeline -->", access_key="timeline", title="Nonverbis: Timeline", priority=3 );';
    return $script;
}

function appthemes_add_quicktags() {
    if ( wp_script_is('quicktags') ){        
        $script = '<script type="text/javascript">';        
        $script = $script . _get_timeline();        
        $script = $script .'</script>';
        echo($script);
    }
}

Problem

At first everything looks great:

But arg2 not working and a slash adds to the button:

It may help: https://codex.wordpress.org/Quicktags_API

Could you help me?