Is Adil Su some type of a Turkish name? I think SU in Turkish means water.
Su means water in Turkish and also in many of the related languages. I don't know about the origin of the name in this case and I don't even dare to guess from which of the many small languages the name Adil Su comes from. Many mountains, places etc. have non-russian names in this area.
The dominating nation living in the region are Balkarians and their language belongs to Turkish group. Most of mountains and location there don't have Russian, but native names, that's why it sound this way.
Thanks for adding the info Artur.