What is wrong with my skeleton?

I’m very much a beginner at this. I’m trying to create a base female mesh in Blender that I can use for characters in a game. I’ve had trouble adding bones and exporting bones in Blender (GameRigTool crashes and SendtoUE doesn’t recognize Unreal anymore), so this skeleton was created in Unreal and I’m trying to retarget animations from a pack in the store. I’ve had great success using auto retargeter in the past, but now it’s looking like this.

Could I ask what’s the use of the extra bone at each joint? Your result seems to be that the bone weights are applied to some wrong bones.

Honestly I have no idea, I think it was the Game Rig Tools UE5Manny