Как сделать в поле Имя Валидация что бы можно было прописывать только буквы

CMS Joomla component Forms Balbooa
How to make in the field Name Validation that it is possible to write only letters.
I have written such a script but it does not work.
jQuery(document).ready(function($) {
function applyValidation() {
// Search for input by field ID (in your case, 1)
const input = $('input[name="1"]');
if (input.length) {
input.on('input', function(e) {
e.target.value = e.target.value.replace(/[^a-zA-Zа-яА-ЯёЁ\s]/g, '');
});
}
}

// Running
applyValidation() immediately after loading the DOM;

// If the field appears dynamically, use MutationObserver
const observer = new MutationObserver(function(mutations) {
mutations.forEach(function(mutation) {
mutation.addedNodes.forEach(function(node) {
if(node.nodeType === 1) {
if($(node).find('input[name="1"]').length) {
applyValidation();
}
}


I've tried other options, but it still doesn't work.
Could you please help me?
The form itself is available at the link
https://schooldance.webtm.ru/forma