I’ll address each of your questions:
- “the language itself” - In order to distribute a non-C++ language integration consistent with the EULA, the language you are integrating must be free (because the EULA requires that such language integrations must permit distribution of a product for free, i.e., not subject to an additional fee).
- “bindings to the engine” - I’d consider that the non-C++ language integration itself, so the answer is yes it must be free.
- “ports of the engine to another language” - I would call this a non-C++ language integration also, so the same rules apply.
- “another language in a game that uses the engine” - You are generally free to do what you want with your game code built on top of Unreal Engine, but there are several restrictions applying to the engine code. I guess I’m not clear on what you want to do with your game code (outside of the engine code).