Write to the Archivist
Questions, shared research, a request to reproduce something, or a note that the site itself is misbehaving — all of it reaches the same desk. Every letter is read, and one that leaves an address is answered.
If instead you know a date the chronicle has wrong, a person it has missed, or a story it never heard, the submission form is the better door — it files such things where they are triaged against the sources.