Hi,
if I remember correctly, one of the main goal for the Composite fork of
Hydrogen, was to get Hydrogen as a LV2 plug.
I just tried it with jalv.select, jalv, jalv.gtk, jalv.gtk3, jalv.gtkmm,
and jalv.qt and all of them gaves me :
Feature http://lv2plug.in/ns/ext/event is not supported
So I would say that the LV2 versio doesn't work.
Last commit is from March 2013 :
https://gitlab.com/composite/composite/commits/master
For my point of view, Composite doesn't bring in anything better that
what Hydrogen does. Hence I'd approve for it to be removed.
Hope that helps,
Olivier