"
Dakota" in
German, for example as used on
German maps for the US, is simply "
Dakota" as well: The name is easy to pronounce for
German speakers, so there was/is no need to alter it in any way.
The
German variant for
James is indeed
Jakob. Note that currently this name is seen as rather old-fashioned in all German-speaking countries, I think that very, very few newborns here will get this name nowadays. Once it was very popular however, maybe 80, 90 years ago or so.