I've been meaning to ask about something regarding this film.
Is four years of college really enough to transform a Singlish accent to an American one? I can't imagine it'd be something that happens naturally unless the person is taking a communications degree. I had a cousin who spent his entire uni life in the UK, and he still speaks English with the same accent he's had all his life.
It really depends on the individual. Some people's accent basically never change from the way they speak since they became adults. There are others who's accent changes like the wind.
I had a classmate who went to Australia and came back with an Australian accent after being there for 6 months. I also had a university school mate who went to Ireland for 3 months and came back with some weird accent that no one can place and he spoke like that for the next few years.
I would say that as a Singaporean, we code switch pretty well in general, even for those of us who have not gone overseas for education. Singlish outside the office, proper English as much as possible in work environment.
One of the points that didn't translate from book to film is that the elders and the rich society in the book perceives Britain to be the defacto choice for sending their kids to further their education. It's a holdover from our colonial days as the old rich in the past before our independence would have received British English education as taught to them by the British and then go on to the UK for further studies. So old money families are likely to speak more like the British.
The mom and her peers look down on Rachel because she's US educated and not UK educated like her son has been. I grew up hearing rich folks who think that the only universities worth sending their kids or grandkids to are the ones in the UK.
In fact it wasn't even dumplings that they ate at the house. It was tea with scones. The movie went above and beyond to to the Asianess of the book. Making dumplings is not an essential part of our Chinese culture because it really depends on which part of China your ancestors came from. My family and relatives never sit down to make meat dumplings together. We're more likely to make zong zi and other things but never the dumplings shown in the movie.