No. You cannot download paid apps for free with Tongbu. You're downloading other apps, not the paid apps. Someone takes a paid app, extracts all the clever programming that does what the app does, then packages it into their own app, which they then make available for free. These apps skip Apple's vetting process because whoever did this also released their own app installer (Tongbu Assistant / iClover) for the iPhone, so they don't need the app cleared for use with iTunes.
Of course, you have no idea what these apps are doing besides doing whatever the app does. For all you know, while you're running an app, as well as doing what it's doing, in the background it's sending private information from your phone to a pirate site somewhere.
So the effect is the same as your users installing any other app you don't know about onto the iDevice you gave them. And the question is the one I asked originally: Why are you distinguishing between Tongbu apps and other apps ? If you have strict ideas about which apps your users should be running, use Configurator or Profile Manager to stop them from running anything you didn't preload onto their devices.