The less contemporary/familar a series is to western audiences the worse the dubs usually are. Inu-Yasha was a mish-mash of modern and historical but it had over-the-top character designs that made it stand out.
Abe no Seimei, I think, has been referenced before in Magical Shopping Arcade Abenobashi. If you watch enough Anime you do pick up on the Japanese History/Mythology after a while.