There's so much competing data to work with it can be really difficult to get accurate translations from what is on the OS. You really need to go back and look at ethnological research from the 18th to mid 20 century (or read a book by someone who has).
First of all OS mapmakers couldn't just take a translation from anyone. They had to be educated men - a minister or teacher, so the thoughts of the shepherd whose family had been there 400 years didn't come into it.
If we look at Càrn an Rìgh, well Rìgh can mean a Lord as well as a king so it could be referring to a Lord of Atholl or Marr (I can't remember where it sits).
Given the preponderance of Ruighean place names and sites in the area I'm actually quite persuaded that it's a mistranslation of Ruighe.
Sometimes knowledge of the genitive case can be helpful and sometimes it's a false friend as in places like Perthshire nobody bothered with the genitive case. In Perthshire and Aberdeenshire the Gaelic was quite distinct from island Gaelic and shared some elements with Irish e.g. eclipsis of verbs Am fear in modern Scots Gaelic would be Am bhfear pronounced am vear.
In some of the last recordings of Deeside Gaelic we hear them calling Càrn an Fhidhleir - Càrn Veeler.
It's also helpful to the local context so I have seen a very weel kent Skye Gael translating Coire nan Giomach in Rannoch as Coire of the Lobster- which is true - but you don't get much lobster in Rannoch. It refers to Rannoch barracks and the redcoat soldiers stationed there. Lobster was a local nickname for redcoat soldiers.
I don't agree with everything John Murray says but his books are still well worth a read. Tìr is Teanga is a BBC Alba series on the origins of Scottish nicknames and is currently available on iPlayer. Watson's Celtic Place names of Scotland doesn't focus overly on mountains but is basically the bible of placename origin in Scotland and well worth a read.
An Litir Bheag and Litir do Luchd-Ionnsachaidh on
www.learngaelic.scot have loads of stories on place names in Scotland but there are thousands of them and you need to do a bit of digging. You can search by topic though