Feedback on the siteTo report a bug on this website, please open an issue in the GitHub repository. That's also where you should visit if you'd like to contribute to the site.
The best way to contact a competition administrator with a general inquiry is to visit the Hanabi Central Discord server; there you can either post in the public #hc-general channel, or DM someone with a Competition Admin role. I'll include my own Discord tag here: Lobster#2222.
If you really dislike the idea of joining that Discord server, you can drop a line in GitHub Discussions.