Americanism has become easier the longer USA has been home to us. As immigrants, we arrived eager to assimilate, but we've had our share of getting stuck in language quicksand with concomitant hilarity and embarrassment.
Our first experiences were totally nutty. To us, "rubber" and "muffler" were benign representations of eraser and scarf. It was mortifying to learn that these are condom and a car part on this side of the pond. We learned not to use these words within a few hours of arriving.
Then there are words that still give us heartburn. Back in India, we speak English without emphasizing parts of words. "Hereditary" rolls off our tongue with equal importance on each syllable - he-re-di-ta-ry. To avoid quizzical looks we learned to belt out heREditary, inVENtry, and VEhicle. Nobody tells you that assimilation means altering your breathing!!
When I submitted my first assignment in an undergrad "Business Writing" class, I left my instructor in splits. The assignment was to write a letter. Mine was littered with kindly, hence, and thus because that is how we were taught back home. When you are amongst a billion people, politeness is non-negotiable. The instructor gave me a list of words I couldn't use, ever. The final submission was half of the original and delightfully crisp. Sadly, the new style will relegate me to the back of the line in India.
I still don't know if we wear trousers, slacks or pants or whether the stuff on top is a jacket or a coat. I have to rely on Tarun to set me straight. When we went from "bu-tuh" to "butterrrr", I practiced in front of the mirror, to see how to roll my "r"s. My accent will never be genuinely American because some of the "r"s get lost in my upper palate.
And learning to deal with "th"sound was epic.
Back in the late 1700s as the colonists pushed westward, they picked up words from Native Americans and Spanish-speaking people. At some point, the national pride in American English overtook adherence to British rules. Contractions - like ain't, can't, don't, won't - simplified the language while words such as bayou, hickory, and squash from Native Americans languages supplemented the American form of English.
A friend who has recently arrived from India is frustrated by my constant corrections on authoritative pronunciation. He generally doesn't object except when I give him a hard time on "event" which he stretches to "eeeeevent". He refuses to adjust on that one, hanging on to his version with extreme pride.
That reminds me of my own Achilles heel - "Guantanamo" - which I cannot say correctly until I flick my head on the "ta".
The good news from my travels is that social media, globalization, and blending of world music is delivering more homogeneity and "American", not English, may become our first language. That would be akin to a "full stop" on assimilation. That is a freebie from me. Feel free to look it up.