With ambush predators like tree frogs, what needs to be borne in mind is that they'll likely ingest whatever their prey was sitting on when they feed. They have evolved to naturally dispose of or pass the things they would encounter in the wild like leaves and soil, but anything spiky and indigestible can be fatal.
Pretty much all the plastic plants I've seen are either made up of smaller components or can easily come apart when grabbed hold of by strong frogs like White's. They have no advantage over real plants and many shortcomings, no need to use them at all really, they're just not appropriate.