I'm a librarian who loves anime, manga, and reading a wide variety of genres.
The first time the Radch encountered the Rrrr, the Rrrr were on a ship crewed by both Rrrr and humans. It has suddenly occurred to me that this could be a nod to C.J. Cherryh's Chanur books. We haven't met any Rrrr yet (unless it happened in one of Leckie's short stories), but their name brings to mind Hani-like creatures. Also, I believe Leckie said at one point that Cherryh was one of her influences.
I'm now imagining a Chanur-Radch crossover.