Thanks for this useful summary!
If there is one thing I would still wish for, it is a very simple, direct example of a concrete case, to show what that could look like when configuring data for publishing through GBIF.org, and what it shows up at (facet filter search, image gallery). That could be just a screenshot of the multimedia section on a page like https://www.gbif.org/occurrence/1265883603, maybe listing the other supported values under the “Type” again, and a few more examples of what else could go under Format in the concrete case. Maybe it could also show where those values come from in the mapping of e.g. a simple multimedia extension (another screenshot?). Nothing all-encompassing and extensive, just the illustration of one concrete case.