The best way to contact the authors and other Survex users is the Survex mailing list - for details visit: https://survex.com/maillist.html
We'd be delighted to hear how you get on with Survex and welcome comments and suggestions for improvements.
And we'd love you to contribute your skills to help make Survex even better. Point out areas of the documentation which could be made clearer, or sections which are missing entirely. Download test releases, try them out, and let us know if you find problems or have suggestions for improvements. If there's no translation to your language, you could provide one. Or if you're a developer, "Say it with code". There's plenty to do, so feel free to join in.