(out of spoilers since it has nothing to do with the WOR)
The Menagerie people = British is just speculation on my part, mostly because I'm pretty sure Velvet is the only one in the entire show who speaks with something other than a generic American accent, and Menagerie seems like it would be the most isolated place in all of Remnant. Though if Beacon was essentially her first experience with Humans, it might explain why she let Team Bully walk all over her in Vol 1 when just about every other Faunus seen so far would have either laughed at them or punched them through a wall.