There is a lot of argument about whether names should be translated and generally both are accepted. The newer trend on Gaelic Duolingo is not to which is probably why this question which is only 5 days old uses Ruairidh as the default in English (which does not mean that Rory is not accepted), even though you may have seen translation in older questions.
What happens in real life is lopsided. People given Gaelic names used to be made to change them at school. This is now regarded as racist and oppressive, so people with these names now generally keep them. But it does not work the other way round. People with English names (like me) tend to use the Gaelic version in a Gaelic context.
The problem with this word is that for most Gaelic speakers, it makes no difference whether the r is broad or slender, so 'whatever suits' is correct in my view.
However, for people in Lewis there is a big difference. You will have heard the slender r pronounced like an English th on this course. Now I have no idea how they pronounce this name on Lewis, or even if everyone pronounces it the same, but clearly the spelling would then have to match the way it is pronounced.
I put Ruari which is sometimes the 'English' spelling. I find it difficult remembering how to spell the gaelic names, so it's quite ironic I end up getting it wrong putting the English version.. But it is good they are translated cos otherwise I'd never know the name Mairead was Margaret etc