Awesome idea for a PREQUEL! Forward to filmmakers lol!
Western film companies should make the story of the magical musician who created the time travel peace before the piano ended up in Taiwan. Maybe take place in old England since it's in english. It could be a tragic romance or maybe with happy ending. Then at the end show how some old forgotten music professor ends up with it and we can assume he's the one who brought the piano to the school in Taiwan decades before XiaoYu and Xianglun's time.
It's totally do-able and would be an amazing new movie with a great story for Western audiences since they may be unfamiliar with this movie...then they can watch this one later! How sweet is that? They can also finally explain why Xianglun can exist in Xiao Yu's time at the end too.