
Since Liam himself is Archie who came to the present day(crossed worlds) , he(Liam) knows of every event that happened and will happen between them.
I think he came into the future a few years before the day when he met mc(like when mc got the antique box). He waited till the day came and handed the box to her so that the her future and the past he(Liam) came from aligned so that they would get to know of each other again.
He didn't say anything because that would change the future(of Archie and mc) and his(Liam) past. Remember ,he said that he would just tell her everything if she insisted?
╰(⸝⸝⸝´꒳`⸝⸝⸝)╯

yes, ive read the spoiler thread that someone gave up there, and even the timeline is hella confusing for me but I reread it to kinda understand it. It's basically a back and forth crossworld but in different time/clock settings. It's kinda like future Candace going to the past but messed up, went back to the future and it was all Dr. Doof then went back to the past to prevent her past future self on doing the same mistake. This made Dr. Doof Future Candace into not existing. The time is kinda like that but crossworlds and without meeting your past self and one of them popping out of existence.

So like it’s sort of your name but like Archie travels to the future (?) as Liam to start everything from the past (actually the future of the webtoon) where he and Cordelia are together using a magic bracelet from her parents that they used to go to the future where cordelia is now living in
Please correct me if I’m wrong ( ̄∇ ̄")
Why Do I feel like this story is gonna f me up at the ending? Like seriously how would they meet up or are we gonna have another "it's better left unknown". Are we gonna have a star-crossed lovers where they follow each other in different worlds? Cause if we get neither or either of that Im in.