YOU SAID:
I’m flabbergasted that you’d think that.
INTO JAPANESE
あなたがそう思うとは驚きです。
BACK INTO ENGLISH
I'm surprised you think so.
INTO JAPANESE
私はあなたがそう思うことに驚いています。
BACK INTO ENGLISH
I'm surprised you think so.
That didn't even make that much sense in English.