YOU SAID:
He said so, to his chagrin.
INTO JAPANESE
彼は悔しそうにそう言った。
BACK INTO ENGLISH
He said this with regret.
INTO JAPANESE
彼は残念そうにそう言った。
BACK INTO ENGLISH
He said this regretfully.
INTO JAPANESE
彼は残念そうにそう言った。
BACK INTO ENGLISH
He said this regretfully.
That didn't even make that much sense in English.