The founding developers were all software engineers with .NET experience, so it was the natural choice even though at the time it was Godot 3.x with Mono. I had used Unity before but not Godot. The project is structured as mostly plain C# DLLs with a relatively thin Godot UI layer controlling it, so the Godot type system is fairly encapsulated. We haven't really seen any issues with those decisions beyond just working out the communication between Godot and DLL. But again we were just working from what we knew so I can't really say if this was the best way to go about it.

We were building on C# Godot and I think it is a second class citizen in the sense that 1) you can't export to wasm and 2) they are moving the interface to be handled by gdextension.

That said, I think once you get the gist of it and understand the landmines, it is really nice to use vanilla dotnet rather than unity's fork.

I have this principle of "5% scripting". If the high level scripting on top of C++ consumes about 5% of frame time, then the language of the script does not matter.