I am an adult native English speaker who can speak one Romance language pretty well and can communicate in and understand two or three others reasonably well enough, and I actually tried to learn Gaelic several years ago by enrolling in an online course provided by Trinity College. I found it incredibly difficult, for I think principally, that it was difficult to frame any reference in sound or grammatical structure to what I had experience of. The influence of the Romans and the Germanic tribes is so obviously missing in Gaelic. I also found it confusing that there are major variations of the language usage within the island of Ireland itself, so that compounded the problem when trying to understand regional difference and similarities. I expected it sound more similar to Welsh, but was surprised to learn that of the Celtic languages spoken in the British Isles (Welsh, Cornish, Manx and Scottish,) it is generally most similar to Scottish. I gave up in the end I am afraid.