I would be fairly sure that Rattling Bog has nothing to do with Rathlin Island off the north coast of County Antrim, Northern Ireland. Apparently there must have been some bogs on the island many years ago (ie pre 20th century) but they have long been cut away for fuel. Some of the small lakes on the island may have resulted from peat cutting.

Rathlin was known many hundreds of years ago (ie BC) to one of the Ancient Roman Historians (?Pliny, I think) possibly because there was an axe factory on the island (there is another at Tievebulliagh Mountain near Cushendall in North-east Antrim, not too many miles away). Such axe factories (using local flint, I believe, though I am no expert on this) were very rare, and presumably axes were in great demand all over Europe, for tools and weapons, etc. One old name for Rathlin is Raghery. A peninsula in Lough Neagh in North Armagh, also Northern Ireland, though now known as Raughlan, is marked on some oldish maps (ie 19th century) as "Rathlin Island". Not far away is Coney Island which some claim gave its name to Coney Island in New York, though I believe Coney Island in Co. Down, and Coney Island in Co. Sligo have also claimed this derivation.

"Rattling" can be a term of approval, as in "rattling good yarn", but possibly (and this is just my speculation) in this context it might mean "quaking" or "shaking". A wet peat bog, such as one might find in a valley bottom, tends to quake or shake up and down if you stand still and jump up and down (be careful you don't sink into the water!).

This is also speculation, but I wonder if the well known Yorkshire song "On Ilkley Moor Bat 'hat" (spelling may not be correct) could be regarded as a similar sort of cycle song. Anyway, just enjoy the songs and don't worry too much about the meanings, and don't take any of the speculations above about the meaning of "Rattling", etc, as gospel.