Translation:Anna and Hilla, you are now married. Congratulations!
As a native I don't find "onnea" being abrupt. Of course if you say it like the computer here does, it is a very dull and lifeless way to congratulate someone. But in real life you hear it very often and that single word can be filled with feeling and life. Feel free to use it. :)
I wonder if they could disable downvoting on the course sentences but still allow upvoting. That would keep the anti-LGBTQ trolls from locking up sentence discussion, although they would maybe be small-minded enough to go into the comments and downvote people making useful and friendly comments about the sentence.
And Pyry is "blizzard" and Otso is "bear". Most everyday English/American names have meanings in other, often earlier languages --Peter means "rock", Carl means "freeman", etc.-- even if they've passed out of common useage, while others like Sage (several meanings!) or Lily are still easily identifiable.