What is the official language of the jurisdiction that would settle any legal argument?
Many T&Cs will have a clause along the lines of "Any dispute will be settled in the courts of..."
In many jurisdictions, the courts won't rule upon documents that are not written in an official language of the country.
This means that you provide your "Master" T&Cs in your home language - let's say English. You can then provide translations into other languages, like Swedish, but they will carry the same clause about the courts of England & Wales.
But remember, if you are getting into the realms of protecting against legal challenges, you will be better served by asking this question of a lawyer.