UCSB adds map titles to the GeoJSON with the element "name" at the top of the file.
Example:
"type" : "FeatureCollection",
"name" : "Ecuador 1:50,000 and Series 3721, 3722",
etc.
Also, the file names are call numbers plus the country. The middle number of the call number is the scale in thousands. Therefore, 4830s_50_e3_Ecuador is a map set of Ecuador at 1:50,000.