Как вывести индекс слайда в блоке TE800 в Tilda

<script>
document.addEventListener("DOMContentLoaded", function() {
    (function () {
    
        const slider = document.querySelector('.t923');
        const sldsMain = slider.querySelector('.t-slds__main');
        const sldsWrapper = slider.querySelector('.t-slds__items-wrapper');
        
        const div = document.createElement("div");
        div.className = "sldbtnwrap";
        div.innerHTML = '<div class="sldleft"></div><div class="sldpostext">1/1</div><div class="sldright"></div>';
        slider.append(div);
        
        const sldpostext = slider.querySelector('.sldpostext');

        let sldlng = '';
        
        setTimeout(function(){
            sldlng = sldsWrapper.getAttribute('data-slider-totalslides');
            sldpostext.innerHTML = '1/'+sldlng;
        }, 500);
        
        const observer = new MutationObserver(function (mutations) {
            mutations.forEach(function (mutation) {
                if (mutation.attributeName === "class") {
                    const sldpos = slider.querySelector('.t-slds__item_active').getAttribute('data-slide-index');
                    sldpostext.innerHTML = sldpos+'/'+sldlng;
        	    };  
            });
        });
        observer.observe( sldsWrapper , {  attributes: true});
        
        
        slider.querySelector('.sldleft').addEventListener('click', function(event) {
            slider.querySelector('.t-slds__arrow-left').click();
        });
        
        slider.querySelector('.sldright').addEventListener('click', function(event) {
            slider.querySelector('.t-slds__arrow-right').click();
        });

    })();    
});    
</script>




<style>
/*Стрелки*/
.t923 .t-slds__arrow_wrapper { width: 35%}
.sldleft, .sldright {
    width: 30px;
    height: 30px;
    background-repeat: no-repeat;
    background-position: center;
    background-size: 100%;
    cursor: pointer;
    transition: all 0.2s;
    background-image: url(https://static.tildacdn.com/tild3337-6566-4365-a264-656462373935/892512.svg);
}
.sldright {transform:rotate(180deg)}
.sldleft:hover, .sldright:hover {
    filter: invert(0.3);
}
/*Контейнер стрелок*/
.sldbtnwrap {
    display: flex;
    align-items: center;
    justify-content: center;
    margin-top: 30px;
}
/*Текст номера слайда*/
.sldpostext {
    font-family: 'Montserrat',Arial,sans-serif;
    font-weight: 400;
    font-size: 18px;
    color: #000;
    padding: 0 10px;
}
/*Скрываем штатные стрелки*/
.t923 .t-slds__arrow { display: none}
/*Уменьшение боковых слайдов*/
.t923 .t-slds__item {
    transform: scale(0.9);
    filter: brightness(0.9);
    transition: all 0.2s ease-in-out;
}
/*Увеличение центрального слайда*/
.t923 .t-slds__item_active+div.t-card__col {
    transform: scale(1.3);
    filter: brightness(1);
    position: relative;
    z-index: 59;
}
/*Уменьшение последнего слайда*/
.t-slds__items-wrapper .t-slds__item:last-child {
    transform: scale(0.9) !important;
    filter: brightness(0.9) !important;
}
/*Изменение картинки*/
.t923__bgimg {
    top: -75px;
    height: 150px;
    width: 150px;
    margin: 0 auto;
    border-radius: 50%;
    box-shadow: 0 0 0 6px #dddddd;
}

.t923__imgwrapper {
    background: none !important;
}
.t923__wrapper {
    background-color: #fff;
}


/*Тень центрального слайда*/
.t923 .t-slds__item_active+div.t-card__col .t923__wrapper {
    box-shadow: 0 0 0 8px white, 0 0 15px 4px #6f6f6f;
}
/*Отступы у колонок*/
.t923__col {
    padding-top: 160px !important;
    padding-bottom: 90px !important;
}
/*Отступы у контейнера*/
.t923__wrapper {
    padding-bottom: 15px;
    border-radius: 15px;
}
/*Отступы у картинки*/
.t923__imgwrapper {
    padding-bottom: 100px;
}
/*Свойства для контейнера*/
.t923__wrapper {
    padding-bottom: 15px;
    border-radius: 15px;
    border: 1px dashed #c3c3c3;
    box-shadow: 0 0 0 8px white;
    overflow: visible;
}
@media screen and (max-width:960px){
.t923 .t-slds__item {
    transform: scale(1) !important;
    filter: brightness(1);
} 
.t923__col {
    padding-top: 90px !important;
    padding-bottom: 15px !important;
}
.t923 .t-slds__arrow_wrapper {width: 10%}
}
li.t-slds__item { list-style: none}

</style>