Not sure about lime/yellow base of plant?... but the other more yellow leaf looks like natural die back to me though I could be wrong.
As for replanting, if it still has buds left to open I would be tempted to leave it till after the buds have opened, or even to flowers have died back completely. Less risk of causing a disturbance to the buds and have them dying off.
Speaking more from experience than cast iron knowledge though
Pretty plant by the way!
Not got any Cymbidiums yet myself.
Great thing about this board though, it has care sheets!
Cymbidium - Orchid Board