It's definitely creative naming,Cheesecake wrote:
A rose often has the connotation of love, you know how in a relationship one might give a rose to the other to be romantic? The song is about love, or more accurately about a lover leaving the character the lyrics describe, so one could imagine said character giving a rose to the person who left her to try and prove her love. Perhaps not the best example, but hopefully that brings my idea across.
So while Rose doesn't directly link with the song, the connotation of a rose and the theme of the song definitely do. It is also of course a play on Hikaru's name there's no denying that, but it's not just some blind memery and there was some thought and inspiration behind it.
But really. When I listen to this song, I wouldn't really call this song is about love. It's a Feint/Monstercat song. Which gives more like a 'cool/upbeat/catchy' feeling than a love feeling. Even when I read/listen to the lyrics I don't catch many love-like things. (more just your average edgy lyrics tbh).
The reason you give for the difficulty naming is too far-fetched in my opinion, "Rose Extra" doesn't fit the song/beatmap.
Of course most people won't even bother thinking about the difficulty name.
But the many other people will think it's a stupid typo or meme.
Only the very few ones who read/have read this thread will realize it isn't a typo and see that the naming actually does have (some kind of/debatable) thought behind it.