Look for structure, not visual size
A bold line is not automatically a heading. Compare the converted Markdown with the source document and confirm that each heading starts a real section. Repeated page headers, table labels, and decorative callouts should not become top-level headings simply because they used a larger font in the source.
Keep levels consistent
Do not jump from H1 to H4 because a source template used four visual sizes. Most knowledge-base pipelines work better with one document title, clear H2 sections, and H3 subsections only where the section genuinely needs another level. Consistency makes chunking predictable and lets a reviewer understand where any extracted passage belongs.
Run a short automated check
Flag documents with more than one H1, skipped heading levels, empty sections, or headings repeated on every page. The check should produce a review list rather than silently rewriting the file. A person can decide whether an unusual structure is intentional; the automation simply makes the exception visible before ingestion.