Hellbox is made by one person, and every report gets read. Pick the door that fits.
The public tracker is on GitHub: open an issue. Search existing issues first; if yours is there, add to it. In the app, Help > Report an Issue opens the same form with your Hellbox and macOS versions already filled in.
Anything attached to a GitHub issue is public. If the report involves a font you can't share, use email instead.
jake@hellbox.com, also under Help > Email Support in the app. Right for confidential fonts, license questions, and anything you'd rather not post.
The docs cover every section type and control, and the changelog lists what each version fixed. Check for Updates inside the app gets you the latest build.