Like @lennart.at.westwing, I haven't been able to utilize the EntityTranslationGestureRecognizer.
The UIPanGestureRecognizer works to move entities around surely, but it's just not great in 3D space & not very convenient.
The documentations suggests that, it is a gesture recognizer that uses a pan gesture to move an entity in 3D space ... but it doesn't seem to work at all.