Wonky/Bent fingures when using Unreal Manniquin - Help needed!

Hi, everytime i import my character with same bone names as Unreal mannequin i get wonky fingers. An experience rigger told me UE mannequin has weird rotation on some bones & animations. How do I get around this? It seems strange how Unreal Mannequin is setup like this, i dont get it.

any help would me greatly appreciated