Contact
Two addresses, read by the same person: one for errors in a published figure, one for everything else.
Report an error
Write to corrections@401kmonitor.com. Include the page URL, the figure you disagree with, and, if you have it, the filing you read it against. The report is checked against the government filing the page cites, a confirmed error is fixed in the next build of the site, usually within days, and the correction is noted on the affected page.
Everything else
Questions, press, data reuse beyond what the licence page already permits, or anything that is not an error report: contact@401kmonitor.com.
Expect an answer within a few days. The site is maintained by one person, so a reply can take longer during a data refresh; error reports are read first.