You europeans could be great for mods involving travelers, the commonwealth, or possible vaults. Since someone could always say oh vault so and so only had european immigrants in it. etc. and the commonwealth is whats left of New England, yanks tend to have european-ish accents occasionally. So thats good well have a good supply of european voice actors. Perhaps a few female voices will pop up soon so we don't see all male characters in these mods.
European refugees would be plausible, and locked in a vault their accents wouldn't have been diluted. Fugees aren't always dirt poor and they have a habit of carrying grudges and feuds to their new homes which gives you more to work with.