I'm not sure. I'm now hearing 3 different takes on Kinshaya, and I'm sure the actual one is completely different...
1. I first heard the name Kinshaya from the FASA RPG Klingon suppliment. In there, they're a bat-like race (close to Man-Bat from DC comics fame), who fought the Klingons tooth and nail on their "coreward border that is opposite the Federation", and are still at war with them, but the fighting is at a casual skirmishing level. According to that source, Kinshaya translates into "demon posessed", a reference to their fighting style, and the fact that the only capture of an intact "dead" body exposed to space vacumn for a short time woke up once "rescued" and it single-handedly slain the entire ship's crew...
The FASA supplement in question is strongly based on materials from, and credits "The Final Reflection" as it's main inspiration.
2. Karnak took and interpreted the descriptions, etc. of the Kinshaya from TFR and called them the Kzinti, a fact that, in SFB-dom, I can understand (the Kzinti are more "coreward" than the Klingons, they share a border away from the Federation, etc. However, I cannot see the "opposite" the Federation part (Feds have a Kzinti border too), and the fact that the Kzinti are not a posessed race. Very determined, yes. Demon-posessed, no. (Unless it's full of Fluf's nuttering away...
)
3. Now we've got someone calling them the Hydrans...
I don't know how they would fit into SFB lore, and I'm not here to try to figure it out...
As there is no Klingon words to reflect my ISC Pacifist nature, I picked a Klingon word that I knew and liked. It just so happens to have a nifty translation too...