All the libraries I have bought/seen advertised say mastered at 24/96. Is this meaning simply that the audio was cleaned up, metadata was added and its ready for drag and drop use? Or is there something more?
In that context I tend to read "mastered" as audio that is edited, problems eq'd out, strange noises removed, etc. Sometimes that can also imply downsampling from a higher sample rate.
I don't tend to read that as having anything to do with metadata.
I also don't take that to imply any sort of dynamics processing.
While I've never used that term to describe my own libraries, I'd assume it just means it was produced, edited, processed etc at 24/96. It's a strange choice of words, as it obviously causes a bit of confusion. I always just say "24 bit audio" in the specs, 24/44 lately.