Separate attachment from selection
VLC desktop's documented external-audio workflow can make another audio track available. Before judging the narration, open the audio-track choice and identify which entry is active. Hearing the original soundtrack does not establish that the external file failed to load.
Use an unmistakable review cue
For your own production, select a moment where the narration differs clearly from the embedded sound. Record the video and audio revisions and the displayed track identity. Avoid relying on a universal track number; the available set can differ between inputs.
Pause the review if the selected audio is ambiguous. A delay applied to the wrong track does not help assess the intended narration and can leave an unexplained setting for the next session.
Keep the selection in the review note
After selecting the intended track, check the cue again and continue the timing review. Record that selection with any temporary adjustment. The result is a reproducible audition choice, not a new media file or a guarantee that the same track position will be selected on another machine.
Questions answered
Does external audio automatically replace every embedded soundtrack?
Do not assume that. Inspect and choose the intended available track.
Should I diagnose sync before identifying the active track?
Identify the selected audio first, then review its timing.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.