Responses
to be fair i think all the very beginning stuff with jian yi being a drunkard and stuff is no longer canon. the actual story of 19 days starts at chap 43, and we do have all the lore, beside some precursors of him being on the supposed island
Yes, I agree that the original idea was greatly developed, the characters changed dramatically, and Mo wasn't even in the plans at first. But as for the plot and lore... we still have no information about where our conventional brothers disappeared to for several years, only to return later.
In fact, it's even funny how the author is like: oh, I'm tired of drawing them as 14-year-olds for 10 years, time to skip ALL THE MAIN EVENTS OF THE PLOT THAT LED TO DRAMAS AND OTHER IMPORTANT EVENTS IN THE FUTURE (see Chapter 1) and just enjoy the side story after the final credits.