Hinterblyr

The Dark Halphards (although they hate being called that), have their own runic language, and have also several percussive sounds made in the palate and throat that are not used in the Common language.
Hinterblyr is included in the Gether Guide to Languages on DrivethruRPG:
https://www.drivethrurpg.com/product/328473/Gether-Guide-To-Languages