Calendar has a lot of scripts indeed each providing extra feature.

I see on your site you're not using much of it.

What you could try is to compress the javascript files into a single file.

Another thing that comes on my mind is to deregister the unused scripts although this has to be tested to ensure we're not breaking something fundamental.

Here's how to remove the unused scripts:

// Deregister unused scripts
add_action('wp_enqueue_scripts', function() {
    global $post;
    if (is_a($post, 'WP_Post') && has_shortcode($post->post_content, 'stachethemes_ec')) {
        $scripts = array(
            'stec-reminder-js',
            'stec-rsvp-js',
            'stec-schedule-js',
            'stec-guests-js',
            'stec-attendance-js',
            'stec-comments-js',
            'stec-forecast-js',
            'stec-location-js',
            'stec-event-create-js',
            'stec-builder-submission-js',
            'stec-sharer-js'
        );
        foreach ($scripts as $handle) {
            wp_deregister_script($handle);
        }
    }
}, 9999);
// Adding dummy functions for the sake of not breaking stec.js 
add_action('stec_after_html', function() {
    ?>
    <script type="text/javascript">
        (function ($) {
            $.fn.datepicker = function () {}; // if your site has datepicker then remove this one
            
            window.StecReminder = function () {
                this.set = function () {
                    return this;
                };
                this.controller = function () {};
            };
            window.StecRsvpToEvent = function () {
                this.set = function () {
                    return this;
                };
                this.controller = function () {};
            };
        })(window.jQuery);
    </script>
    <?php
});