My interview is in 2 weeks, and I just spotted a typo in my application

Ah well.
Not sure if I really have any advice, but something I wish people had told me when I was working on my app is that don't let too many people to critique your essay. If you're working with a consultant or maybe a friend, definitely get their feedback as you go along, but there really is no need to ask too many people for advice. Everyone has their own narrative and their own way of expressing themselves, and while they have your best interest at heart, it is, at the end of the day, your own story, and even good advice can cloud your own sound judgment. Your way of crafting the narrative will show not just in the essay itself, but also eventually in your interview as well.
I would also read the essay out loud as well, and see whether you've written something you would actually say. The prompt, after all, is introduce yourself to your section mates, so I think rather than focus too much on the written rhetoric, focus on the content and delivering the true you instead.
Hope this helps