I think part of the problem is all the voice acted scene are always serious. There isn't many scenes to show a full range of emotion. All the scenes that are voiced really require stoic seriousness, with precious few exception usually in the character personality.(Like Tataru)
I personally think they Nailed Lady ice-heart and Merlwyb(sp), also Alphinuad and Y'stohla put in solid work. The rest are ok but again all seriousness. I think if characters were showing more emotion Lyrailis would be spot on.(I can't say how the Japanese voice actors sound.)