It has other options, like GDNative: https://godotengine.org/article/dlscript-here

See for example: https://github.com/GodotNativeTools/godot-rust

It just sounds like another glue language. The reason UnrealScript halted development was because they found that its whole purpose is to call C++ code. So they put their focus into making Unreal a more reusable framework instead of confusing developers with some zainy little toy programming language project that serve as an interface.

This allows using any language really, as long as you can produce a shared library that matches the ABI/API. Which should be good enough for those who have some issue with a particular scripting language.

What is wrong with that example?

We already know by its value it's a float. It's literally easier to type that in C as float x = 5.0;

GDScript can infer the type by writing it as var x := 5.0. I'm guessing it's just the authors preferred style to include the type.