This is one of the first things I've noticed since watching the drama and thought it was really cool so I thought I'd share. While Ildeung's is 100% obvious, the other two could possibly be just my interpretation but I still think it was intentional by the author. I posted this in the comment section too but it'll eventually get drowned under new comments, so I'm making a post here for preservation's sake!
Na Il Deung: "na/나"means i/me and "ildeung/일등" means first place. "na ildeung" can be translated as "i'm first (place)", just like how in the drama, he always thought he had to be the best in class and beat his classmates for the top score.
Yoon Ah Yi: ah yi's name in hangeul is written "아이" which means child, likely referencing how after trying to force herself to grow up, she rediscovers her inner child over the course of the drama, eventually believing in magic.
Ri Eul: In the webtoon, his pseudonym is just ㄹ, which is the hangeul letter for R/L and is pronounced "rieul/리을", hence the name here in the adaption. perhaps more of a personal guess, but ri eul sounds like "real"; as a magician who is used to nobody believing in his magic, all he wanted was for people to believe that it's real.
Those three are the only ones I picked up on, I'm not sure if any of the other characters' name have meaning to them too, but those three are the most important anyways. Still, I think it's something quite neat and clever of the author to do, it's a nice detail and gives the characters some more substance.