"The dessert my older sister made is really pretty."
I translated the sentence, "The dessert my sister made is really pretty", as 我的姐姐做了的甜点真漂亮 and was marked wrong. The accepted answer, 我姐姐做的甜点真漂亮, seems like it should be the translation for the sentence, "The dessert my sister MAKES is really pretty", rather than the aforementioned.
Google Translate seems to agree: 我的姐姐做了的甜点真漂亮 = The dessert my sister made is so beautiful. 我姐姐做的甜点真漂亮 = The dessert my sister makes is so beautiful.
I feel like I'm in the right here, but don't want to flag it without a better understanding of the uses of 了. Can anyone link to a grammatical rule which demonstrates why Duolingo's translation would be the preferred one, or should I just go ahead and flag it?