Default language settings should pull your country of origin from Steam/console profile in order to determine best audio settings. E.g. I’m from the US so default settings should be to include English audio instead of English subtitles.
I’ve played over 100 hours of this game’s content and don’t understand the plot at all because I had no idea that this setting existed.
Maybe this should be asked once starting the game for the first time, ie:
Welcome to Generation Zero, would you prefer Swedish or English audio dialog?
‘Swedish dialog button’ ‘English dialog button’
Great idea, that’d be perfect!
I don’t know about others but every new game i buy, after launching the game and arriving to Main Menu, i go into Settings and look over every single setting game allows to be changed, including Graphics, Audio, Gameplay and Controls. Once i’m happy with the settings, then i start the New Game.
It’s a good practice to have. 
Though, on devs perspective, i understand why Swedish is set as a default audio dialog. 
It’s Swedish made game and they like to promote their language. Nothing wrong in that.
Country of origin wouldn’t be the best option since while you may live in a X country, it doesn’t mean that you like to use the country’s official language in the game.
Moreover, many countries have several official languages. For example: Switzerland. In there, official languages are: German, French, Italian and Romansh.
Which of the 4, game should choose, if it detects you being from Switzerland?
Btw, USA doesn’t have official language. USA is multilingual where English and Spanish are the two most spoken languages. Here, same problem rises, which of the two languages game should choose? English or Spanish? Or when considering minority, one of the may other languages spoken in USA (Chinese, Korean, Bengali, Arabic etc)?
For catch-up: Generation Zero story timeline
Which is why lolex500 has the best solution: ask when starting a new game.