The title you wrote was "N을/를 축하하는 뜻으로", but your last Korean sentence doesn't follow this pattern. (What you wrote) 언니가 집에 돌아오는 뜻으로 파티를 했어요. So, 언니가 집에 돌아온 것을 축하하는 뜻으로 파티를 했어요 would be consistent with your title, and this sentence sound natural to me.