I just found out I can add a specification table per language. My workaround:
– Select other Language (e.g.) Dutch in the top navigation.
– Create new attributes.
– Create a new group.
– Create a new table.
– Translate a product via WooCommerce Multilingual.
– Navigate to products.
– Click on Dutch.
– Click on edit.
– Add the table we just created. And fill in the information.
This is not a real translation, but it works.