Hi,
It's an issue with how the tags system of Joomla is done.
The name and description of the product is stored in the ucm_content table when the product is saved.
When com_tags displays the results of a tag, it look into that table and directly takes the name and description from there without asking HikaShop.
And thus, HikaShop doesn't do any query to load the product information to give it to the tags system.
However, the way Falang works is that it looks are the MySQL queries and replaces the data based on the translations.
So Falang doesn't have anything to replace in that case.
You would need to have a contentelement xml for the ucm_content table so that you could translate the core_title and core_body columns of that table in Falang and in that case, they would be translated. But that's twice the work for you.
From my point of view, I would try as much as possible to not use tags. Instead, try to use a custom product field with a filter, or categories, etc.