It would be freaky if you opened the door and there was someone (standing) there. If there were someone sleeping there, it would be even scarier.
ーIt would be freaky if you opened the door and there was someone (standing) there. If there were someone sleeping there, it would be even scarier.
「ドアを開けて誰か（立って）いたら怖いよね。誰かが寝ていたらもっと怖いよね。」
It would be freaky if... で「もし…なら怖いよね」という言い方です。
it would be even scarier で「もっと怖いよね」
ーI think it would be kind of shocking if you opened the door and someone were there and if someone were sleeping in bed, it might be even more frightening.
「ドアを開けて誰かがいたら驚くだろうね。で、もしベッドに誰かが寝ていたら、もっと怖いだろうね。」
it would be kind of shocking if ... を使って「もし…なら驚くよね」と言えます。
it might be even more frightening で「もっと怖いかもしれない」
frightening で「ぎょっとさせる・驚くべき」
ご参考まで！
It would be scary if someone was there when you opened the door! It would be even scarier if someone was sleeping!
「開けた瞬間誰かいたら怖いよね！寝てたらもっと怖いっていう」を英語で表現するには、次のように言うと自然です：
・It would be scary if someone was there when you opened the door! 開けた瞬間、もしも誰かがいたら怖いよね！
「scary」は「怖い」という意味で、「if someone was there」は「誰かがそこにいたら」を意味します。
カナダ 
アメリカ合衆国 
