YOU SAID:

their eyes couldn't believe

INTO JAPANESE

彼らの目は信じられなかった

BACK INTO ENGLISH

Their eyes were unbelievable.

INTO JAPANESE

彼らの目は信じられないほどだった。

BACK INTO ENGLISH

Their eyes were incredible.

INTO JAPANESE

彼らの目は素晴らしかった。

BACK INTO ENGLISH

Their eyes were wonderful.

INTO JAPANESE

彼らの目は素晴らしかった。

BACK INTO ENGLISH

Their eyes were wonderful.