That's really helpful! So if you contact the POI and ask the reasons of rejection they will tell you? I really wanted to know why I got rejected (well I am sure there would be a lot but it would be nice to know where can you enhance). After all the EAS department in Harvard is the only place I wanted to go for the past two years. I really wish my POI could tell me why I got rejected, yet I was afraid of bothering her.
Congrats for being admitted by Columbia! It's a great program despite locating at NYC hahaha. I am saying that because I am one of the EALACs at Columbia now. Welcome!