Hi Brendan, you're correct about the water landmark and the event being related to the number of the crossword. So you're on the right track.
The moved letters don't seem to spell anything. I wondered about the children's song too, and the letters of its name appear randomly among the moved letters, along with others which won't belong in the song at all (K and Y for example).
I'm still unsure of exactly which 44 cells need to be outlined. There aren't enough moved letters to make 44 cells. But if you outline all the modified answers (including cells which don't move), there are too many cells.