Yes, Yhdysvallat is correct, you can also note that the "state" dropdown menu shows all american states when "yhdysvallat" is selected.

Yhdysvallat is a quite straight forward translation of united states
Yhdys= united/unified vallat = states (=authorisation to rule, have power to rule)

Lastu seems to be minimal in communication (but here at north we do, we don't chitchat : ) : ),
I just ordered for my Jolla Tablet a lastucase . Got order comformation , and no communication after that , then one day(less than week from order) the case was in the mailbox.