Mai Natsume may be an alias but it's what most people in the story call Mai and is the name that is used to select her in the game itself. Mai Hazuki is her real name but Mai Natsume is much more recognizable, so I think it's what should be used on the wiki both on her page and on other pages, especially when refering to Mai after she joined the academy. Someone unfamiliar with Mai won't realize who Mai Hazuki is if they read that name in another article since Natsume is what's normally used for her.
Vladimir Lenin was simply an alias used by Vladimir Ulyanov but the former is the name most people know and the one he's listed under on Wikipedia.
No, Mai didn't officially change her last name to Natsume. She registered at the military academy under that name, but when Shori and Chachakaka checked her records they didn't find any mention of a previous name or any other past information. Chachakaka referred to her as Mai Hazuki, and both her parents and Kagura considered her to be a member of the Hazuki family.
Eryops, thank you for clearing that up! I saw your message much earlier, but I was very sleepy, so after 8 hours "nap" I can respond!
So, about naming the article... I changed it to "Mai Hazuki", mainly because we name character pages by their real or full name, so that's why for example page Tager's page is not named "Iron Tager", but it is "TR-0009 Tager" I know it's not his real name, but more like, I don't know, serial name. Where Mai is needed to be called "Natsume", there she is called, because on some Remix Heart history sections it would sound ridiculous to call her "Hazuki" when certain characters don't know about her being a Hazuki.