I have reached Yuki nirvana
Well, they're not on stage in front of a live audience so less energy is to be expected. Though I wouldn't really call Wakana an energetic singer hue.I think it's about Yuriko and Joelle just not sounding as energetic as her in the more upbeat songs.
I also thing Yuriko and Joelle are blending better in both songs than Yuriko and Wakana. Wakana tends to stand out instead of blend in.