Validate content comprehensibility using calibrated Student Simulator prompt-personas (alto rendimiento, promedio, necesidades especiales) for age-appropriate readability. Trigger on: comprensibilidad, legibilidad, student simulator, carga cognitiva, validar contenido, readability, age-appropriate, pre-filtro, perfiles estudiante, simulacion lectora, accesibilidad contenido. Runs 3-profile simulation scoring legibility, cognitive load, and engagement per section with quantitative thresholds and fragment-level flags.