“en.products.product.add to cart”
Typically this should be “en.products.product.add_to_cart” with underscores and no spaces.
You’ll want to try and find this line of code in the related product template files or possibly the javascript if this infact only ever appear when the variant changes.
product templates would be product.liquid , product-template.liquid, snippets or sections like product-card.liquid,etc
javascript is typically in theme.js
If your using apps that modify products on the website in some way that could also be a root cause.
To get translation errors professionally fixed contact me at paull.newton+shopifyforums@gmail.com with store url, storefront-pass, this topic url and any other related details.
