Eureka! I finally stumbled onto the English version of Daria on MTV 2. As a bonus, MTV France and MTV 2 seem to be synchronized, which means I’ll watch it in English two days after seeing it in French, and I’ll be sure to understand everything properly. (Not that I need that, obviously.)
As seems to happen a lot with American TV cartoons, the French voices are rather similar (as far as main characters go) and even possibly better acted out than in English — for once, the French expertise in dubbing has its advantages. Too bad the musical episode has already been shown, I’d have liked to compare.