The overall score
The 0–100 % score combines DTW distance on MFCC features, duration match, pitch and spectral centroid. An A means a close match; an F means a clear mismatch.
Why a similar sound can score low
Check your trim: extra silence at the start or end shifts the alignment. Keep only the working fragment in the editor.
score = 0.55 * dtw + 0.15 * duration + 0.15 * pitch + 0.15 * centroidWarnings do not change the score directly, but they show what to fix in the next attempt.