YOU SAID:
His mom was doing the wrong thing
INTO JAPANESE
彼のお母さんは間違ったことをしていた
BACK INTO ENGLISH
His mom was doing the wrong
INTO JAPANESE
彼のお母さんは間違っていました
BACK INTO ENGLISH
His mother was wrong
INTO JAPANESE
彼の母親は間違っていた
BACK INTO ENGLISH
His mother was wrong
Well done, yes, well done!