YOU SAID:

To my surprise, the twins flounced off the bed.

INTO JAPANESE

驚いたことに、双子はベッドから飛び降りました。

BACK INTO ENGLISH

To his surprise, the twins jumped off the bed.

INTO JAPANESE

驚いたことに、双子はベッドから飛び降りた。

BACK INTO ENGLISH

To his surprise, the twins jumped off the bed.