Hi,
Well, it depends on how your website is configured and how the languages are setup. I suppose that you'll need to add the language tag in the URL, but maybe it also means changing the alias of the menu item...
The simplest is to use the content tag plugin:
www.hikashop.com/support/documentation/1...-product-insert.html
It will generate the add to cart button based on the current situation and on top of that, it will support the HikaShop cart notification plugin to display the notification, refresh the cart module areas etc. Finally, since it will handle things dynamically, it should have no problem with different languages.