Yosef Karo

“ It is forbidden for a chazan to read the Megillah until they say to him, "read" (Mordechai ch. HaKoreh) .
סעיף א
קורא אדם את המגילה בין עומד בין יושב אבל לא יקרא בצבור יושב לכתחלה מפני כבוד הצבור: הגה ואסור לחזן לקרוא את המגילה עד שאומרים לו קרא [מרדכי פ' הקורא] :
690:2 Even two or even ten people can read at the same time and they fulfill their obligations and the obligation of the people listening to them. ”

“ However, if [the Megillah] was written in Hebrew script and one reads it in Aramaic to an Aramean, the obligation is not fulfilled, because the reader is reading by heart; because the reader does not fulfill the obligation, the listener does not fulfill the obligation. ”

“ And if the reader is the chazan we assume that he intends to fulfill the obligation of all listeners, even if they are behind the synagogue. We are not precise about correcting errors. And there are those who say this specifically applies to linguistic errors where the content is unaffect, like that case when two students were sitting in front of Rav, one read "Yehudim" and one read "Yehudiim," and neither had to repeat. ”