The C# version of the project is separate from the main one. It is possible to entirely code a game in c++ though in the main one (you can use both c++ and gdscript in it in one game interchangeably). Gdscript is a really easy language to learn though and is similar to other scripting languages (the only things you really need to learn is some keywords godot added to make coding in it easier when using things in the engine. Stuff like node names etc you would have to learn regardless of the language you’re using)