I disagree that GDScript is a poor builtin language. It is somewhere between Python and JavaScript. It gets the job done and there is a lot you can do with it. Signals are great for things like state management. I'm not really sure what you mean by spaghetti code and how signals are supposed to help. I do agree that there are some annoying OOP aspects like providing a path to a scene (module). It's verbose but not unlike library imports in other languages.
When using the optional typing in GDScript, I'm surprised at how many errors are caught before runtime. The optional type syntax is nicer than Python's and the auto complete is good.
Godot could have built on Python, but they would have had to also include a language server (and maybe ipython or jupyter or something) to get the full seamless experience that GDScript gives. Including all that seems a bit much.
So, like you, I appreciate GDScript and have sympathy for why it was created.
Also, GDScript hasn't done anything like implicit type coercions (see JavaScript) and so GDScript can improve without breaking backward compatibility. If needed, breaking backwards compatibility in GDScript won't be as bad as breaking backward compatibility in a real programming language, so they can steer it where it needs to go for the benefit of Godot.
