@AmyLove.

Regarding your first set of lyrics:

"How grand are the houses the Peelers live in"

I think the term "Peelers" is achronistic here. They were 19th century policemen. The Rapparees were about in the late 17th century to the early 18th.

"The Spoilers" is the word I've heard. I haven't found any reference to that term online, but I would imagine from the historical context that it refers to the new colonists or their descendants from those turbulent times.

The song has the characteristics of a 19th or 20th century historical balled in my opinion.

A compelling narrative and powerful melody.