I will definitely be using this. However it is missing some data. For example, filtering on author: aquinas yields nothing, but see https://librivox.org/author/1199?primary_key=1199&search_cat...
For example, you can query using only the first letter, so it's quite easy to quickly cache their entire collection (please don't give them the HN hug of death):
https://librivox.org/ ... api/feed/audiobooks/author/^a
Of course, specify json or something closer to your internal data structures.