If we could only be so lucky as to have insects actually form breeding populations in our vivs! That's kind of the holy grail of sustainable viviculture but the high predation rates from frogs in small vivaria make this impossible to do in a conventional viv. If you feed meadow plankton, you will get the odd hole chewed in a leaf by something before it goes down a frog throat but I've rarely seen major damage. I've even had grasshoppers hatch out in vivs and start munching away on plants but the frogs quickly take care of them. In my opinion, the minor damage done adds a more natural character to the viv. In fact, I kind of wish it were possible to keep more plant munchers going in vivs. As you've discovered, getting plants to grow in a viv is not the hard part. However, there can be some specific pests. Millipedes, slugs, snails, and sometimes pillbugs have been known to set up shop in vivs and some of them will eat frog eggs. Some of them will also chow down on certain plants. Orchid roots and buds seem to be a favorite with the millipedes in one of my vivs. That said, I've had some orchids growing in that viv with millipedes for years but other orchids have perished because the millipedes ate them. Sometimes they will kill a plant but the same species of plant in a slightly different location gets along fine. I actually think such challenges add to the fun of keeping a vivarium.