The list for music is basically arbitrary anyway. It's only vaguely organized by specific game, and even then some base game songs are just flat out either in the wrong spot or attributed to the wrong game (like the Animal Crossing Wild World theme says it's from the original Animal Crossing, while "Melee Boss 2" is a song from Brawl, but the list claims it's from Melee).
So the fact that Dreamland and Miiverse have their music spread through the list, versus all in a clump is something nobody would ever notice was "wrong." And considering how weird the list already was, it may not even be "wrong" I just thought it was interesting Dreamland and Miiverse were treated like stock game music as far as the list is concerned.
And this is entirely different on the 3DS, as well, where Dreamland is at the end of the Kirby songs, just like the other DLC stages. But I have yet to figure out any pattern to the 3DS list anyway lol.
Never, ever try to make sense of the trophy order either. You're hurt yourself. I gave up pretending it was even close to being organized by anything. Even with the sorting options, they lie sometimes (sorting by series place the Pilotwings trophies all over for some reason, for example). And this was before DLC. The DLC is actually fairly logically placed for trophies, other than they are tacked onto the end. But this is the same trophy list that says Jigglypuff is an unlockable Brawl vet and Doctor Mario is either the last Brawl character or the first Smash 4 New Comer lol, so it's not like the base game was very organized either.
And to make it even funnier, sound test and the classic mode videos are in an entirely different order based on the order the characters are unlocked on the 3DS lmao. So starters like Ness and Ganondorf are down with ROB and Game and Watch on the list because of reasons I guess.
imo all character lists in the game should be listed by what Smash the series had a character added, and within that, organize by starts and unlocks (based on what they were in their original game). All music should have the series organized by what Smash they were added (as they are now), and within organized chronologically by when the original game was released. Sub series like Mario Kart can continue to be organized in their own "block" as they are now. This is sort of how it's organized, but a few songs are misplaced or mislabeled. The 3DS doesn't appear to have any logical order.