YAML is not merely JSON with fewer braces. It can name nodes with anchors, reuse them through aliases, attach tags, use complex keys and carry several documents in one stream. Plain conversion can flatten or reinterpret those features.
Rejecting is safer than guessing
JSONYAML rejects anchors, aliases, explicit tags, directives, multiple documents, duplicate keys and non-string mapping keys. The source must be made explicit by its author before conversion, so a hidden expansion or last-key-wins rule cannot enter the result.
The destination parser is authoritative
Keep the original, diff the complete output and parse the result with the exact library or application that will consume it. JSONYAML proves only that one bounded document fits its declared JSON-compatible profile. It does not validate a destination schema, environment substitution, application defaults, deployment behavior or semantic correctness.
Comments are presentation, not JSON data
Ordinary YAML comments may be read, but JSON has no comment value, so they are omitted and the result evidence says so. If comments contain operational knowledge, move that knowledge to reviewed documentation or a schema description before conversion.