> You make the comment a child node of the object literal node, don’t associate it with the following key/value pair at all. When you pretty print it, it will have the same relative order with the following kv pair as it had originally (and you cannot reorder json keys safely because the handling of duplicate keys is implementation-defined).

Many implementations parse objects into hash tables and lose duplicates and even order of appearance of name/value pairs, and all of that is allowed. Such implementations will not be able to keep relative order of comments.