Brendan Breathnach thought most older Irish reels were of Scottish origin, and Alois Fleischmann's book traces the Scottish (and often English) originals for most of them. By the twentieth century Ireland's reel industry reached the point of satisfying domestic demand. (For jigs, the story was more or less the other way round, as Irish jig farming seems to have been more intensive than in Britain).

No traditional tune known from either Scotland or Ireland can be shown to have any origin from a Celtic culture elsewhere.

Many tunes now played as strathspeys were originally published undotted. That was because they were played as reels at first and only strathspifficated decades later (example: Carraig's Reel, which became The Smith's a Gallant Fireman). You can't guess the exact dotting pattern of a strathspey so it has to be put in explicitly.

An anomalous one: John of Badenyon. The 18th century sources for that all give it a systematic hornpipe-like dotted rhythm. But it wasn't a hornpipe, it was a slowish song. It's most often played these days as a reel (a Cape Breton "wedding reel"), very fast and with no dotting. If it ever had a hornpipe stage in its evolution (fast-ish and dotted) there's no trace of it.