I personally know that Paku is the japanese way to pronounce "Park" a korean last name.... so i'm guessing maybe Park Romi is 2nd or more generation korean japanese.
Here is the Japanese site that I went that has a decent listing of Park Romi thus far: http://sdb.noppo.com/romi_p.htm - acoording to it, they describe her as "韓国語" which means Korean (language) so i'm guessing she can speak/write Korean.
It's really really rare for a non japanese to be a seiyuu. Well! Looks like Americans CAN go to Japan and become seiyuu for those of you who truly dream of it ^^