Before one of my colleagues gets assigned to your support request, let's try the most common solution when translations get their stock levels out of sync.
As a general rule, I would recommend running a full backup before any bold operation.
Please, go to WooCommerce Multilingual > Status > Troubleshooting inside your installation, and find the option Synchronize stock for products and product variations. Check it, and click the button to run the selected troubleshooting tools.