but Momoyo is totally Bi.
I'm not sure about that, she just plays and entertains girls. This is probably because boys around her aren't just manly enough to her (it doesn't help she's an absolute juggernaut that will intimidate any guy). Shouichi is the only one worthy but he's not interested in romance until that single moment in Momoyo's route, and Yamato is her "brother" but she was disappointed when he forgot about his ambition. I think Momoyo explained this herself in the VN, but I don't remember when.
Also, on localization. I have come to dislike localization as a type of translation. Trying to mold the piece of work to fit better in the target language is silly IMO. Take Majikoi for example, it's a Japanese work, written by Japanese, for Japanese, the work is impregned in Japanese (culture etc...). The Japanese particularities of the work is also part of the work, not some accessory you can just replace with another country's particularities. As you are one bothering to read another country's work, it burdens on you to familiarize that country way of thinking/culture (as the work is most likely influenced by those anyway). The resulting work may sounds goofy in your language, but it probably has an explanation found in the original language (bonus point to the translator making a note about it).