Lux's W shielding her instantly is okay in my opinion.
But please, don't go through those E buffs
She'll be WAY too oppressive with it, as any good Lux player will always land it correctly (even now, it's almost impossible to dodge, unless you got mobility)
Give her something if you want, like a small mana regen buff or something, but please, don't go through with that Lux E change.