Medium Editor multi user with fake caret

Question

I'm trying to build a collaboration text editor using Medium Editor (https://github.com/yabwe/medium-editor). What I'm trying to do is to implement this functionality into my editor:

https://github.com/convergencelabs/html-text-collab-ext

I'm not really an expert on Javascript and I'm facing some issues. So far I created a Medium Editor extension that listen from the external users input, taking in input the caret position of the external changes (using the exportSelection() feature of the editor). What I'm trying to do now is to insert the fake caret (similar to the one seen on html-text-collab-ext) in the position where the changing was made, but of course without touching the real caret.

My Code:

    export const CollabAnchorPreview = MediumEditor.Extension.extend({
        name: 'collab-anchor-preview',

        init: function () {
            this.anchorPreview = this.createPreview();
            this.getEditorOption('elementsContainer').appendChild(this.anchorPreview);

            this.subscribe('externalWriting', this.showPreview.bind(this));
        },

        createPreview: function () {
            var el = this.document.createElement('div');

            el.id = 'medium-editor-anchor-preview-' + this.getEditorId();
            el.className = 'medium-editor-anchor-preview';
            el.innerHTML = this.getTemplate();

            return el;
        },

        getTemplate: function () {
            return '<div class="medium-editor-toolbar-anchor-preview" id="medium-editor-toolbar-anchor-preview">' +
                '    <a class="medium-editor-toolbar-anchor-preview-inner"></a>' +
                '</div>';
        },

        destroy: function () {
            if (this.anchorPreview) {
                if (this.anchorPreview.parentNode) {
                    this.anchorPreview.parentNode.removeChild(this.anchorPreview);
                }
                delete this.anchorPreview;
            }
        },

        hidePreview: function () {
            if (this.anchorPreview) {
                this.anchorPreview.classList.remove('medium-editor-anchor-preview-active');
            }
            this.activeAnchor = null;
        },

        showPreview: function(external_caret_position, editable) {
            console.log('Event');
            console.log(external_caret_position);
            
            // Here I don't know well how to go ahead.

Thank you very in advance.