It took me 2 minutes to find these:
- Can I use C# for Unreal Engine 4.9? - Programming & Scripting - Epic Developer Community Forums
- https://forums.unrealengine.com/unreal-engine/feedback-for-epic/25346-i-want-feedback-from-epic-about-mono-for-unreal-engine?54595-I-want-Feedback-from-Epic-about-Mono-for-Unreal-Engine=&highlight=xamarin
- https://forums.unrealengine.com/community/general-discussion/32028-c-in-ue4
- https://forums.unrealengine.com/unreal-engine/feedback-for-epic/1774187-any-plans-for-another-scripting-language-besides-blueprints-c
- https://forums.unrealengine.com/unreal-engine/feedback-for-epic/1782573-add-more-programming-languages
- https://forums.unrealengine.com/community/general-discussion/1768092-my-wishlist-for-ue5
- https://forums.unrealengine.com/community/off-topic/76237-cryengine-has-adopted-a-pay-what-you-want-model
- https://forums.unrealengine.com/community/general-discussion/78038-mono-relicensed-under-mit-c-for-ue4-can-come-back
- https://forums.unrealengine.com/unreal-engine/feedback-for-epic/82514-the-mono-project-likes-scripts-does-epic-games
- https://forums.unrealengine.com/community/general-discussion/87559-dotnet-core-release-at-devnation-2016-and-news-about-c-f-for-ue4
- https://forums.unrealengine.com/community/general-discussion/20879-use-c-to-script-in-unreal-engine-4-now-courtesy-of-xamarin
- https://forums.unrealengine.com/unreal-engine/feedback-for-epic/92039-blueprints-are-a-toy-which-serious-unity-dev-would-use-ue4-without-c-f-or-unrealscript
- https://forums.unrealengine.com/community/general-discussion/110073-unrealcs-unity-alike-c-plugin-for-unreal-engine
- https://forums.unrealengine.com/community/general-discussion/70421-why-is-unity-the-most-popular-engine