Unfortunately, Hydrognomon is unsupported. Read the first question in the FAQ for more details.
There is a a page and a community group in Facebook. You could try joining the group and posting any questions there, though it’s not certain you will receive a response.
You can contact (some of) the developers and maintainers by emailing email@example.com, but, again, you won’t necessarily receive an answer.
Hydrognomon has been developed by the Itia research team of the National Technical University of Athens, Greece.