I enjoy my Killarney's and would recommend them for bang for the buck. But they do seem to have a tad harder push than my Sindts between octaves. . Since you seem to have a bit of an advanced case of WAOD (or is it WOAD?) i recommend you get yourself on John Sindt's list. It is not as long as it used to be, and he, like the rest of us, is advancing in years. So I have no idea how long he will want to continue to make whistles.
The Killarneys are Sindt knock offs. And they do a decent job. But my Sindts play with a fluidity and ease I don't find in my Killarneys.
But I have happily played my Killarneys in sessions and heard them played well by many. So I don't intend to knock them here.
A year or so ago I saw an ad for a Chinese made Killarney look alike, a knockoff of a knockoff

. And just this week I have seen postings on the Chiff and Fipple Facebook page of an Ireland based company selling whistles that look like Killaneys with the caveat they are "finished in Ireland." So I wonder if someone is buying some of the Chinese made whistles and fine tuning them.
The notes you mention as being off may be unique to your instrument. These are manufactured and I am not sure how much attention is paid to fine tuning them. I am sure they try, but at that price point I am not sure they can spend a great deal of time on each whistle. If you think you got a whistle that is far out of line talk to them. I am sure they would want to make it right.
As for whistle tuning. I have found the tuning of a whistle (and flute) is not fixed like on a concertina or piano. It varies while playing and most of us consciously or unconsciously are working our instrument to play in tune. Some are easier than others.