Edit Synthesia midi notes (not particles) – Adobe Support Community

Midi notes are made on 3rd party software usually, like MuseScore. You can add and remove notes there after importing a midi. Then if you export the midi file that you edited and added it to Synthesia, you can record that and put it into AE to add some VFX like in this case the particles, a glow and maybe some CC or the other effects like images, added into the notes and flickering smoke like effect.