GrapesJS Block Attributes not shows in config when I load the HTML and CSS

Hi, I'm beginner in GrapesJS, I want just create a block with some custome attributes, when I drag and drop the block and I select the block, if I see the config menu I've the new attribute than I've added: twitter title and I can modify it, but when I save the HTML and the CSS and I've reload the page, the HTML and CSS are loaded right, but if I select the block I can not change the twitter title attribute, I let you the code. Thanks

 const editor = grapesjs.init({
            container: '#gjs',
            fromElement: true,
            height: '600px',
            width: 'auto',
            storageManager: false,
            blockManager: {
                appendTo: '#blocks',
                blocks: []
            }
        });

 var blockManager = editor.BlockManager;

 //Add Twitter Feed Block
        blockManager.add('twitter', {
            name: 'Twitter Feed',
            category: 'Blocks',
            label: '<b>Twitter Feed</b>',
            name: 'twittertitle',
            content: {
                attributes: {
                    'wac-block': 'twitter',
                },
                traits: [{
                    label: 'Twitter',
                    name: 'twitter-title',
                    type: 'text',
                    value: '{{ platform.title }}'
                }],
                activeOnRender: 1,
                content: `<div class="block">Twitter Feed</div>`,
            },
            attributes: {
                class: 'fab fa-twitter fa-1x'
            }
        });

For save the code I do this:

textarea_css.value =  editor.getCss();
textarea_html.value = editor.getHtml();