"Ni äter en måltid."

It is, when addressing an individual. "Ni" is how you would address multiple people or a plurality. Kind of like saying "you all". If you were talking to a dating/married couple - and you wanted to ask how they met, you would use "ni" to include both of them in the discussion. It's the "royal you", if you will.

I don't know if you speak Spanish but it would be the "ustedes" form meaning like "you all". Of course it's conjugated differently in swedish than in Spanish but you get the gist.

en translates to both. :)

I'm afraid we have no way of affecting the "type what you hear" exercises.