Order confirmation page language

I am using WPML for handling the translation.

After the payment has been done and customer is redirected back to the merchant page, the language of the confirmation page is reset back to website default one.

That happens on my local installation (using version 2.5.6) as well as online demo: https://demo-shop.maksekeskus.ee/wpml/pood/

Expected behaviour:
After payment has been done and customer is returned to a merchant page, the language is preserved (same as it was before leaving the page).