You enter notepad++, and you use the "search through folder" function.
And you search after "Você matou" not "Você matou 1 dragon lord's." since thats wrong.
Search after "Você matou" and you will find what script it belongs to, open it and you will see the whole sentence, half of the sentence will be script language, so it catches how many dragon lords you killed. Then just modify it, translate it to English if ur smart.