It's basically a reference implementation. Their library should not do any work other than marshal data. Kind of like how Amazon produces a command line tool to interact with their API, but you don't have to use it. It's just a lot easier.
the problem is that when an producer publishes a library like this, it's very tempting for them to assume that all access will go thru that library, and maybe even that all access will go thru the most recent version of that library
it takes an enormous amount of discipline to ensure that this kind of software is treated as "a reference implementation" rather than the canonical path
if an internal service API is too difficult to use without an API library, then this is a pretty good signal that something is wrong and needs to be fixed, imo
in fact the galactus team should actively _not_ publish a library for their API
doing so introduces a source-level coupling between consumers and producer, which the API was (presumably) created specifically to avoid