You can check out ch 43 for a quick reminder of the scene you mentioned!
Hwanseong got discharged from the hospital before Jihoon / Wonjae's body. He never attended the funeral himself, but heard about it from a neighbour, so he believed it.
So far, we didn't get any explanation for this confusion / mistake on Hwanseong's part, but seeing the recent developments, I think that maybe the neighbour confused Wonjae's death with his grandpa's death? Since a few chapters ago we found out that Wonjae's grandpa died before Wonjae even woke up after the accident (or at least that was my understanding)
Ohh actually guess what?
I checked the Korean version of ch 43 and I think there might've been a mistake in the original translation.
What the neighbour actually says is: They moved out right after the funeral. (not "the boy's funeral", like it was originally translated). As we know now, Wonjae's grandpa died then, so I think that's what the neighbour was talking about, but Hwanseong assumed it was about Wonjae ('s body / Jihoon), since it made more sense for him
Wait..didn't jihoon's friend (the taekwondo guy) said he attend/saw Jihoon real body's funeral? The friend even asked youngmin how come you a friend don't know his death..Did I missed something?