ご質問どうもありがとうございます。
様々な表現があると思いますが、いくつか自然な表現を紹介します。
1. An open kitchen is great as you can communicate easily with someone in the living room, but the downside is that all the smell spreads towards the living room.
((( --- downside = デメリット ---)))
((( --- "as" は "because"との意味です ---)))
2. An open kitchen is great as you can communicate with someone in the living room, but the smell can easily spread towards the living room.
お好みに合わせて使い分けてみてください。
ご参考にしていただければ幸いです。
If you have an open concept kitchen, you can have a conversation with people in the dining/living room, but the cooking odours end up in the living room, which isn't so good.
この場合、次のような言い方ができますよ。
ーIf you have an open concept kitchen, you can have a conversation with people in the dining/living room, but the cooking odours end up in the living room, which isn't so good.
「オープンコンセプトのキッチンは、ダイニングやリビングの人と会話ができるが、料理の匂いがリビングにも行ってしまいよくない」
ご参考まで！
ドイツ 
カナダ 
