I think the fans of the artistes she's covering are just jealous/upset/bitter that Kuu like outdid those songs than the originals. Omg I'm such a Kuustan
Seriously speaking though, I'm not THAT surprised at how much ETERNITY is selling; reli, I'm not expecting Kuu to sell like her Black Cherry days anymore, and JUJU, Koubukurou & SUPERFLY can sell reli well for their cover albums but yeah... it's just not that important anymore xD