The Capcom USA names really don't work. It doesn't help that to this day Balrog is the Crazy Buffalo and all his moves are all Buffalo / Bull / Bison named.
Spanish name aside, Vega as Balrog works since Balrogs are tall, lanky, scary monsters. What's Vega with the mask on with claw? A tall, lanky, scary monster.
And Bison as Vega is whatever, but you know what they say about the Spanish Inquisition...
The names as they are now are fine because it's been too long, same applies to Gouki/Akuma, which makes no sense really. Gouki made more sense since he is Gouken's brother. Also you literally lose the reference when Akuma becomes Oni, since the Ki 鬼 in Gouki 豪鬼 is also read as Oni by itself.
Oni can be translated as demon, but these kinds of demons in traditional Japanese folklore are more like ogres.
The localized name of Akuma 悪魔 is basically a demon of the Abrahamic religion kind, which is really different.
Way to go Capcom USA! But they own SF now and without their constant pushing of SF we wouldn't have the franchise still since Capcom Japan has no clue on how to run their company anymore outside of failed attempts at mobile, Nintendo moneyhats for Monster Hunter, Ace Attorney and Resident Evil games. So it's a lose-lose anyway you look at it.