CustomTextField (Cart) - Can't set via Code

I created a product page, that uses the $w(‘#shoppingCartIcon1’).addProductsToCart to add a product to the cart. This works perfectly fine. However, after a customer buys something the customTextField value is not passed along. Everything is stored in the Stores/Orders Database except for the customTextField value. It seems weird that one would not be allowed to add a customTextField value, but everything else…

export function button1_click(event) {
let product = [{
"productID": storeItem._id,
"quantity": $w('#input1').value,
"customTextFields": [{
"title": "customText",
"value": var1,
}, ]
.then(() => {
console.log("Product added", product);
session.setItem("shoppingCart", "1")
.catch((error) => {

CustomTextFields (customTextFields)

Description : Displays any custom fields you may have set up in an array of JSON objects.
Type : Text
Can connect to data : No
Can use in dynamic page URL : No
Can be sorted : No
Can be filtered : No
Read-only : Yes

So you can’t set CustomTextFields in via $w(’ #shoppingCartIcon1 ').addProductsToCart? Seems weird that they include it as a option there if it is Read-only… Would definitely be a great feature.