Patches, bug reports and feature requests should be posted to the SourceForge trackers.
Feedback is always appreciated!
If JHylaFAX is not yet available in your favorite language or localization for a particular language is incorrect or incomplete you can easily step in. The translations are hosted at a Launchpad project that enables localization through a web interface.
Here is a bit of background information about the facilities. To get started right away, create an account and goto the JHylaFAX translation page.