I once had the reason to call a friend of mine a wanker (because of something extremely silly he had said (as a joke)). A Glaswegian who heard this then asked “Why do you call him a wanker? He’s not from the East coast of Scotland.” :rolleyes:
Which illustrates that there’s more to swear words than their literal meaning, because “jerk”, and to a lesser extent “jerk-off”, have now been adopted in the UK, but are considered much milder than “wanker”. I imagine that in addition to adopting these words, we’ve also adopted their perceived mildness. Or perhaps most British people don’t actually know what they mean, as with “wanker” in the US.