"We finish our meal."
Translation:Nous terminons notre repas.
My understanding is that this should be allowed, although it's a more stilted phrasing. "finir" is about ending something, while "terminer" has the connotation of seeing something through to its end. So, you are more likely to see your meal through to the end rather then simply stop it, but both should be valid.
I guess if we look at it from Duo's point of view, if they had accepted it we wouldn't have been alerted to the difference between the words.
By simply making us repeat an example and feeling slightly put upon we end up remembering a subtle difference in usage.
Whatever works and doesn't kill you is worth doing I suppose.
Of course your answer is right! You can use 'finir' as well as 'terminer'.
Finis ton repas et après tu pourras regarder le match (Finish your meal, and then you can watch the game).
Mais on va dans un joli restaurant intime, et quand on aura fini notre repas, tu pourras me jeter de l'eau (But we are going to a lovely, intimate restaurant, and after we finish our meal, you can throw water on me).
both are acceptable J’ai fini mon repas = J’ai terminé mon repas / I finished my meal.
Two other things influence whether you would choose finir versus terminer: the rhythm of the phrase – sometimes finir just sounds better in one situation, and (se) terminer might sound better in another. And literacy level – some people might argue that terminer is the more sophisticated word choice in situation where both are acceptable.