I don't know of any Gaelic version, and I haven't seen anything to indicate that the English language version of "Carrickfergus" is very old. What is the earliest proven date of a text or tune for it?

The only tune known as "Carrickfergus" through 1865 is the one also known as "The Small Pin Cushion", "Haste to the Wedding/Rural Felicity" and "The Dargle". You will find all of them listed at |1284| in the Irish tune index on my website. The tune title "Carrickfergus' is said to be related to a ballad about the taking of the castle there by a French force under Admiral Thurot in 1760, but I haven't found a copy of the ballad. There's more than one ballad about the defeat of the French and death of Thurot at the battle of Sole Bay, a few months later, but none that I've seen called for that tune. [A note in Linscott's 'Folk Songs of Old New England' on the composer of the ballad (Thurot according to her) is obviously completely garbled. Nothing new as far as her comments on other old songs and tunes go.]