https://wiki.openstreetmap.org/wiki/Multilingual_names#Scotland
https://wiki.openstreetmap.org/wiki/Scotland#Gaelic_names
I urge you to read these wiki articles. OSM doesn't follow council statements, rather common practice and what's on the ground. In places where language speakers are at least roughly 50/50 (e.g. Na h-Eileanan an Iar, Belgium, Switzerland) we have two or more values in the name tag. The only region where Scots Gaelic is the majority is Na h-Eileanan an Iar, where you can see the name is already in Gaelic. If you want to be able to see the Gaelic name in place of the English name you are welcome to create a renderer that prefers name:gd.