It is not an ACH. It's an ending. I don't know if it doesn't trigger haven't you talked to the kid in the leather shop. But I got it everytime I finished the game. All two times that is.
Interesting, I did talk to that child (several times, like with most npcs to see what dialogue variation they have) but all he talks is how his uncle Buba sends him books, wonders how big market in Noer supposedly is and how his incle has the shop in Noer city.
His adoptive father is saying something along lines of how young are the future and how important it is for them to go and see the world.
I did the ending several times (in one continuous save-file but in different stages of progression) with the most recent after doing Cocona final quest, but everytime I do get - in regards to the fishkinds -typical stuff of how after Noer island was depopulated they went back to reclaim it but were forsaken by Sea Witch and after a few decades were extinct. There was not any picture of that airplane - I guess it must be somekind of a bug.