There's no math to do :s
One Piece is published in Shonen Jump, that is a teen-oriented magazine, as its very name implied.
There's no younger people that onboarded later OP, but only older people that stayed (as you and me;)). The target is always the same: male teens.
Same age, but that means you typed wrong date in your profile, because its written "39" in the forum.
And for the same reason I assumed he wasn't enjoying so much... Read OP as an adult gives you different feelings
I was 22 when it was first published in my country, now I'm 49 and it still gives me the same feelings... And in fact I continued to buy the volumes.
Where is the problem?
As they already said to you, it was in chapter 1056 (she discovered it in 1055), that's the panel:
Bitchy Robin vanished after Enies Lobby, that's a fact.
Maybe you should re-read last 3/4 arcs, because you seem to misremembering a lot of things...
Robin has great love for her crewmates, as we saw during Wano's battle with Black Maria; she informed immediately the crew about Pluton being in Wano, and Luffy even said that he doesn't care about it...
Gorosei and God Knights probably will die immediately after Imu death's, for what we know.
The real problem is: how the heck BB and his crew can reach MJ? Rocks infiltrated during reverie and is barely understandable, but now? Even food can't reach red line's peak.
Only thing that comes to mind...