'Ae, pololei 'oe. Yes, you are correct. In English the word "e" before a proper name does not actually need a translation. I am thinking they added "Hey" to have a match for the word "e" to help people remember that it needs to be there in Hawaiian.
2 possibilities - it accepted it as a slight typo, OR perhaps the creators allowed both answers. In reality, singular and plural are actually a bit fluid in Hawaiian. I like bananas is acceptable as Makemake au i ka mai'a.