Events.js previously firing, now it is not

Have you simply just tried using the code from the example to see if that works for you, plus as Shan mentions above that you don’t need to add the import for Wix Stores either.
https://www.wix.com/corvid/reference/wix-stores-backend.Events.html#onCartCreated

Also, note that if you test it just on preview mode that it won’t work for you.
Note
Backend events don’t work when previewing your site.

Finally take note of the code examples here from Adas as you have an extra semi colon on your insert line.
https://www.wix.com/corvid/forum/community-discussion/stores-order-hooks-not-working

Tested it with this code in a published site:

import wixData from 'wix-data';
import wixStores from 'wix-stores-backend';

export function wixStores_onNewOrder(event) {
 let newOrderId = event.orderId;
  wixData.insert('Logs', {'orders': newOrderId})
}

orders is a reference field in Logs collection, so it shows me the the order from Stores/Orders collection.

import wixData from 'wix-data';
import wixStores from 'wix-stores-backend';

export function wixStores_onCartCreated(event) {
 let total = event.totals.total;
  wixData.insert('Logs', {'title': total})
}

export function wixStores_onNewOrder(event) {
 let newOrderId = event.orderId;
  wixData.insert('Logs', {'orders': newOrderId})
}