That info is not currently on the site. I'm sure that info would be available by contacting the historian or curator of the collection. The depth of information varies from flag-to-flag and is sometimes open to debate which is better left in forums like this.
I believe the intent on the site was to offer just images in the "gallery" section with the understanding that people could request more information if desired.
More images of other flags will be added over time. There is an inventory in the info section.