Seriously…It’s not that hard. I’m Australian. I don’t say my American character is eating a biscuit and a packet of crisps, then going to the fish and chip shop after they put on their trousers. I do my best to have my Scottish character use correct Scottish slang and terminology - and the girl acts like I’ve slapped her mum when I just let her know that she’s having a character say things that just don’t make sense in the setting.