Perhaps you could extend an invitation to Yohann to this thread? Since the documentation is in French, the invitation should probably be written in that language by a native speaker.
The Djehooty introduction mentions Gramps several times. Maybe he would be interested in collaborating so that the 2 might work seamlessly? Or at least exchange data? I recall no indicators that Gramps will be expanding its media object cataloging capabilities in the near future.
The description of tracking provenance and cross-referencing with meta data is intriguing. And vaguely reminiscent of our discussion (in another thread) of tracking artifacts.