Upon reviewing the JSON file you provided, it appears that the product is displayed in Danish, which is the primary language for this item. The backend of the order page displays the translated version of the Danish product.
Could you please verify if you receive the Danish language for all other secondary languages when placing an order?
I will consult this with our 2nd Tier Support. Do you have a simple way for us to generate the JSON file that you shared? I'd like to demonstrate the issue to our 2nd Tier Support in my report.
I've heard back from our 2nd Tier Support, and they've suggested that this might be a natural behavior of WCML.
To further investigate, we've set up a sandbox site at this link: hidden link, where regardless of whether we check out in English or Dutch, the order information consistently remains in the primary language.