And yet I have always felt “copacetic” (meaning, very good / excellent / completely satisfactory) to be a rather elegant and inspired word-coining (not that I actually use it much); whereas “cromulent” – like “copacetic” for you – makes me want to “go postal” on its users. Conclusion, maybe: we’re strange creatures, and our instinctive likes and dislikes don’t make sense and are not consistent – they’ve no need to do or be so, they just are.
Whilst bugs me too. It seems that mostly UKers tend to use it a lot in places where normal Americans would just say "while. Why that makes it annoying, I dunno, they use lots of silly words, but it does.
I’m American and I’ve always used a lot of “British” words. Like spilt and spelt (vs spilled and spelled) as well as whilst and amongst. In fact, just the other week I looked up when to use “among” vs “amongst” because I didn’t know the difference and found out they are the same.