Welcome to our forum. Yes, you didn't say how old your bengals are. Kittens may be more prone to falling than adult cats. And most cat trees provide platforms to allow to cat to climb up and down. If yours did not come with these, then you bought the wrong cat tree or if the platforms are too small, they may tumble off. My 15 pound DSH has fallen twice off the top sleeper. My 11-year old bengal can't walk across the back of our couch which is 5" wide without nearly falling off. So, clumsy they can be.
Usually cat trees are places where the cat rests or sleeps. If yours have too much energy, which bengals have, then you nee to engage them in play time. Do not rely on the cats to amuse themselves. Bengals get bored really easily. And they are very social cats. The want to be and interact with their humans.
It sounds as if you are not a "cat" person. Bengals can be challenging as they are nothing like your regular domestic cat. There is a lot of GREAT information on this forum and out on the web for you to read. And know above everything else -- your kitties are behaving normally because they are bengals. I have to tell myself that every single day with mine.