The Titans are a group of lifelong friends. Their naming sense isn't gonna be based on achievement but how much they love each other. Roy Harper Academy makes sense. If it's awkward when he comes back, then awkward it is.
The Harry Potter comment has the same effect to me as a Wonder Woman supporting character playing Arkham Knight, the Supersons Family discussing the difference between Batman 66 and Superman 78 theme song, or Jon Kent Naruto-running, which is just an amused "heheh".