I got really excited about the idea of an Avocado relative that tastes like the cross between and Avocado and a Coconut, so I did a lot of digging into this earlier this year. There's a guy named Jay Bost at University of Hawaii who went to the native region and visited many small towns asking about it, and wrote a couple of research papers on it. He also got folks from towns in the region to bring their best fruit for a tasting event. The thing is, I don't know if anything happened with the seeds from that fruit -- whether they planted seeds from the best fruit or not.
I also asked about the history of the specimens that were in the University of California collection. There was a small grove of them planted at UCLA in the early 1900s but it seems that they were lost or cut down when UCLA stopped being the main site for the agriculture collections. I emailed the CRFG list and got (indirectly) a reply from Julie Frink at the UC field station in Irvine, and she said:
"We have an avocado that it called G755C and is an avocado X Schiedeana that was going to be tried as a root rot resistant rootstock. The tree gets huge, does flower, but hasn't had any fruit, at least in the last 22 years."
I think it'd be exciting to find and propagate two types of schiedeana -- one line that's more of the onion-y flavor and one line that's more of the coconut-y flavor.