It's not 'technically' a backhop. It IS a backhop. The opponent just crosses back over it and ends up behind you.
f+B is inputted the way it is because moves are always inputted with relation to the opponent's position.
i.e. If you're facing left and the opponent is on your right then you input it to the right, but the move will still come out facing left.
I've been messing with this recently as a midscreen HD combo:
2B, 2B [HD] 2C, 623C [DC] 214AC, [walk under hop] 6B, 6B, 6B, 6B, 6B, 214D [DC] 236B, 623A [DC]* 426A, 623C [DC] 426C, (optional 624624P), 6246AC
It's quite easy with a little bit of practice. Hell, I mess up the initial psycho sword input more than I mess up the rest of it.
(* If you want to show off, you can DC into another 214AC here and send them to the moon twice in one combo)
(note: input psycho sword DC into command grab as 641236 and double tap punch)