I'm British and I use the word. "They've gotten good". Coders in particular have to learn American and a lot of us just use American on the internet unless we're talking in an English (or UK - English, Welsh, Scottish, North Irish) corner of the interwebs.

Or even Cornish! I was pleasantly surprised to find Cornish written across the side of the buses whilst visiting Plymouth. It's not much more than a linguistic and cultural curiosity, unfortunately, with even the excitement of the Cornish Revival being wholly insufficient to reach a critical mass of contemporary speakers. However, if there's just a faint possibility we'll be able to preserve the tradition I'm all for it.

Whatever happens the pasties will live on forever.

It does exist (in that British people are aware of the US usage and "ill gotten gains") but sounds like a clueless person talking, or a child, so unless deeply exposes to American English nobody would use it themselves. I'm beginning to, but only after 30 years in the colonies.

Hm. Listen some more! We use it in the US Midwest routinely. Had gotten dehydrated. Have gotten bit by that issue. We've gotten the flu around here pretty frequently this winter.

Then there's misbegotten, begetting, begotten.

mixing British and American English is also common for European non-native English speakers

You shall know by the assembled slang what series they watch