Hi,
not sure whether you have already HSearch setup as a project, but this
https://www.hibernate.org/462.html might help you if not.
Next step would be to join the
hibernate-dev mailing list. There you can summarize your ideas and start a discussion about what you want to do.
If your ideas turn out to be good, you probably should create Jira issues for them to make everything traceable. You can then attach patches to these issues which someone with commit privileges will then review and apply.
I hope this answers your question. Help is always welcome and I am looking forward to hear from you on the mailing list :)
--Hardy