>>>Before America, at my Russian school, we were taught British English.

Back when I was in France, one of my friends prevailed on me to help his kid brother with English. They teach Brit English there too - and it didn't go well.

More recently (but still a multiple decades ago) I spent time in NZ - mostly on motorcycle, but some visiting. I bought my friends then-toddler a book about 'Pippins and Whales', which meant I was reading it to her on repeat (duh - but my first toddler experience). My friends were unhappy with the way their daughter pronounced 'whales' after that - and I still can't hear the difference.

Speaking of 'can't hear', I never got to the point where I could hear the difference between 'ami' and 'amie' (male and female friend, respectively) and never ditched the accent - to the point that pretty much everyone I met asked me where my guitar was - they had no doubt about where I was from.