The connection to the name is superficial though. Sure there are similarities between the power of Geass and the geasa but the emphasis has been changed significantly. Same with Ragnarok and the other mythological elements I guess. Geasa in mythology are quite odd and fascinating, more symbolic than simple tasks. Like Cú Chulainn's dog meat/free dinner geasa
But Geass
is the official name, appears in the logo and is what Sunrise have elected to call it. Spelling mistake or not, it's their decision. When the R1 dvds are released do you think Geass will be changed to Geas in the licensed subs? Somehow I doubt it.