I think it's neither. I certainly wouldn't claim "Superbe" is a French word, but I'd bet it was designed to evoke France. If it's a French word, the "e" on the end would be vocalized as a subdued "uh" sound, with the "u" sounding as a long "oo," and the "e" sounding as the "ea" in "bear." There would also be a stress on the second syllable.

soopear'buh

See, high school French wasn't useless after all.