Recognizing that there may be formal process requirements that make it difficult, it would be nice to see the reporting system be as easy as possible. The current informal process says:
if you are being harassed in an 18F space, please speak to the organizer/admin of that space. If you can't reach them or are uncomfortable talking to them, any member of the 18F team can put you in touch with 18F Acting Executive Director Aaron Snow or Deputy Executive Director Hillary Hartley. GSA employees also have the option of raising their concerns with the Office of Human Resources Management or the Office of Civil Rights.
These are a lot of options, and require a fair amount of decisionmaking and effort on the part of the reporter. Additionally, they require a reporter to reveal him or herself--both by speaking with a representative of 18F and, at events, by publicly approaching that person--in order to make the report. It's possible that this has a chilling effect on making reports.
One possible alternative is to create a page on the 18F site with a form for submitting code of conduct reports. That form can send the report by email to the appropriate people, post in an appropriate Slack channel, or whatever else you want. Ideally, this form would have optional name and contact fields, so that reporters can choose to submit anonymously where privacy or retaliation is a concern. To make things easier for 18F, that page could also include some text about what information is useful as part of a report. It should also be clear where the report will go once submitted.