Jargon glossaries sound like a great idea! (I'd be very excited to see them integrated with the wiki.)
A post I quite like on the topic of jargon: 3 suggestions about jargon in EA. The tl;dr is that jargon is relatively often misused, that it's great to explain or hyperlink a particular piece of jargon the first time it's used in a post/piece of writing (if it's being used), and that we should avoid incorrectly implying that things originated in EA.
(I especially like the second point; I love hyperlinks and appreciate it when people give me a term to Google.)
Also, you linked Rob Wiblin's presentation (thank you!)-- the corresponding post has a bunch of comments.
I suspect people overestimate the harm of jargon for hypothetical "other people" and underestimate the value. In particular, polls I've run on social media have historically gotten results where people have consistently expressed a preference for more jargon rather than for less jargon.
Now, of course, these results are biased by the audience I have, rather than my "target audience," who may have different jargon preferences than the people who bother to listen to me on social media.
But if anything, I think my own target audience is more familiar with EA jargon, rather than less, compared to my actual audience.
I think my points are less true for people in an outreach-focused position, like organizers of university groups.