I perhaps ought to have also mentioned that yes, all of these
files are in completely different formats. It's somewhat maddening,
but there is no "standard" for orbit formats, and none of the existing
formats is compatible with other objects (some can't handle comets,
some can't handle natural satellites, and so on). It's a bit off
topic for this group, but I'll mention that I'm trying to push through
a "universal" format :

https://www.projectpluto.com/orb_form.htm

Getting astronomers to agree on something like this would make
herding cats look easy, though. But I have some projects I'm working
on for which a common orbital element format is pretty much of a necessity.

- Bill