The rebuild of unstable is currently triggered once a day. Then, after the job set builds successfully (including tests). You can track it on https://howoldis.herokuapp.com/
There is no proper way to report things outside of GitHub at the moment but many contributors read Discourse so they might be able to report an issue on your behalf.
Unfortunately, Discourse does not really work with patches so until alternative method of contribution is established, creating a pseudonymous GitHub account is your best bet.