Multiple wp_editor instances in custom post type using Ajax

forget about using wp_editor on such scenario.. instead use the core tinymce, something like;

tinymce.init({
            //selector: 'customEditor-' + nextPlusSignId,
            editor_selector: 'nwac_editor_' + nextPlusSignId,
            mode: "specific_textareas",
            media_buttons: false,
            menubar: false,
            content_css: nw.baseurl + '/skins/wordpress/wp-content.css',
            body_class: 'mce-content-body nwac_plus_signs_' + nextPlusSignId + '_template post-type-products post-status-publish mceContentBody webkit wp-editor wp-autoresize html4-captions has-focus',

        });