This may be an indirect reference (Mabey even false, because I was too pronancing it Lye-Fa). But, the Lifa tree made me think of Arise (FF4) the second level of Life Magic. You know Fire->Fira. Why not Life->Lifa(Arise). There's even Life 2 in FF6.

And of course the reused fiends of element also reminded me of FF4 Lich(MilonZ), Marilith(Rubicant), Taimat(Valvalis), and Kraken(Kainazzo). The reason I didn't think of FF1 at the time is that I didn't know they where in there at the time I played FF9.