The JSX fingering field is declared but never rendered — a real, currently-shipping defect, not a hypothetical

Any note field an author can legitimately set is expected to affect the render; a silently-ignored field is worse than no field at all, because authors have no way to discover the gap short of visually checking every lesson.

General API-design/engraving-tool-integrity principle, not a specific Gould/Read/Ross citation — this is a Gradus implementation defect, verified directly against source.

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.