Funny enough it actually mentions in the Wikipedia article that most Americans are unfamiliar with the slur. I'll be honest without this thread if I heard someone say it, I would probably have used it unknowingly just assuming it was similar to Aussie or something.

This is not to make light of the slur, but if someone called me an "Ameri" I would probably just assume they're French, which might be meaner than anything they're trying to say to me.

Is Spaniard not the correct term?

I’ve heard people say “Pakis” as a short for Pakistani in a non-insulting way

Non-insulting according to whom? Some people are so ingrained to racism that they don't even sound racist. It's like old people who say "negro" but don't mean to offend. They're just unconsciously recycling the racism in which they were indoctrinated.

Ah, but it is such a fun word! Shortening it takes out the fun of saying the full Pakistani.

Imagine me when I first got to Australia as an Englishman to see a big headline in the newspaper saying something like, "Pakis lose to England".

I was like, Whaaaaaaaaat !!!!!!

I've now been here 32 years and I sometimes explain to Aussies that Brits aren't allowed to use that word, which they're rather surprised about. Because as you said in your last two sentences.

Cheers.

Which is hilarious, because in new England a "packy" is a package store, which is a euphemism for a liquor store.

So I got quite a few looks when I asked if we were going to "hit the packy" on the way to the party....

Its actually mildly interesting, are there other slurs that really wouldn't be slurs in another country? The F slur would be one I suppose is just a cigarette for some people?

Entomology? I'm not sure where insects come into it.

Isn't Brit a British term originally? I'd guess that'd the reason it's considered different