In my experience growing a ton of plants (I think I'm up to ~75 species or so) under various artificial lights in and outside of terrariums, it depends on potting mix and habituation. Ficus should be able to take a fair amount of water. I have one growing with my poison dart frogs, and while there is drainage, it stays pretty wet. I also have the same kind of ficus as a houseplant, and it never gets nearly as wet.
That said, a plant that is used to low humidity and drier conditions that gets stuck in wet conditions can just rot because it's not used to it. Similarly, if it's in a potting mix without much aeration, it can probably still drown. I recently drowned a schefflera in a new setup, which was surprising because the established schefflera in with my chameleons have rooted through the false bottom directly into the water and are fine. But this was a plant that wasn't used to substrate as wet as the setup was, and it just didn't take.
I'd recommend trying again, but this time maybe put a drainage layer in the bottom of your pot and up the light a little bit. All of this combined (dome fixture, LED light, bag of leca) should cost ~ $30 plus the cost of a new ficus. You could also try a Schefflera instead - I think they're a bit less finicky than Ficus, and they're a bit sturdier too for the chameleons to climb on. Also, consider a light meter. I purchased a light meter to read foot candles for around $15 on Amazon. It was a good tool in terms of teaching me how quickly light dissipates in a tall vivarium and what kind of fixtures I would need to actually get acceptable penetrance.
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