Per the Declaration of Arbroath Scots Gaelic isn't indigenous but would have instead been introduced by the scots when they genocided the picts (note this didn't actually happen, probably). I also find it somewhat unlikely that we are going to find someone who can read ogham.

In practice the number of Scots Gaelic speakers appears to be falling rather fast and it isn't our job to counter that. The number of Scots Gaelic speakers who don't speak english or the lowland scots dialect of english is also nill so english should suffice.