I tried to addEventListener to form from FormContainerBlock.ascx with a code like this, I tried about a 100 different little variations but no matter what, I could never get event to fire during submission.

<form method="post" novalidate="novalidate"
          data-f-metadata="<%: Model.MetadataAttribute %>"
          enctype="multipart/form-data" class="EPiServerForms <%: validationCssClass %> clearfix form-horizontal" data-f-type="form" id="<%: Model.Form.FormGuid %>">

    <script>
        const guid = "<%: Model.Form.FormGuid %>";
        const addEventHandlers = () => {
            $$epiforms('.EPiServerForms#' + guid).on('formsSubmitted', function (event) {
                console.log("intercepted");
            });
        }
        
        if (typeof $$epiforms !== 'undefined') {
            console.log("epiforms exist");
            $$epiforms(document).ready(addEventHandlers);           
        }       
    </script>

The only thing that acctually intercepted submission was this code 

[InitializableModule]
[ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
public class FormEventsInit : IInitializableModule
{
    public void Initialize(InitializationEngine context)
    {
        FormsEvents.Instance.FormsSubmitting += Instance_FormsSubmitting;
    }

    private void Instance_FormsSubmitting(object sender, FormsEventArgs e)
    {
        // The event fires before the data is submitted so there is an opportunity to interact here
        var formData = e.Data;
    }

    public void Uninitialize(InitializationEngine context) { }
}

What I need to do is to add some data realted to google analytics when form is submitted. So I need to access window.dataLayer object, whis is present then. I thought I'd be able to intercept through script and add it then but not working yet. I can intercept submission via IInitializableModule, however can window be accessed here ?