Can we use godot with the C# integration for the jam or only supported platforms are allowed?

Hi - Backtrace doesn't have a direct godot integration, but you are free to look at the native crash reporting libraries we have and make use of those in your game if they work. https://support.backtrace.io/hc/en-us/categories/360002096212-Integration-Guides has some of those details. 

Hope that helps!