| Issue | Explanation | |-------|-------------| | | Users with color vision deficiency may struggle; the author later added shape‑only variants. | | Limited repertoire | Currently only 30 melodies, all in Western major/minor tonalities. | | No built‑in progress tracking | The Discord bot provides random drills but does not log performance. |

The authors conclude that the Melody Marks approach yields a statistically significant improvement (p < 0.01) in short‑term melodic recall compared with conventional interval‑drill software.