Hi Gianluca,
Thanks for responding. I took a look at your guide, and I definitely understand the gold standard would be to get everything translated professionally, and provide a completely native experience.
Unfortunately due to our catalog size that would be prohibitively expensive, so I need to think of another solution. It sounds like from your guide that we are doing more harm than good, even with alternate language syntax in place.
Based on your answer, my thought would be to meta noindex any product page where the site language is not the same as the product. That way every page in the index will be 100% localized for potential visitors.
So if its a Spanish product index: site.com/es/product, but meta noindex site.com/de/product, site.com/product, etc.
If we follow that path, does it make sense to remove the alternate language syntax, since all the linked URLs will be no index?
Thanks again for your help.