I know you can use C#: I have used C# and C++ in my Godot projects. However, other languages are not first class citizens in Godot. When I say GDScript isn't a real language people may interpret that as me being hostile towards Godot. In reality I'm just frustrated because I think the Godot editor is nice, but it's not capable of creating the types of games I want to play. GDScript is not used outside of Godot, and therefore it complicates the task of developing a shared commons of open source editor tools. For me, a criteria of open source is that it works with all toolsets, not just derivatives of a specific environment.