It looks like your hand is deforming to fit the tracked hand data using *Should Deform Mesh *option found here (https://.com/leapmotion/leapunreal#deformation)
https://i.imgur.com/LhIu3JQ.gif
For this to work your model should have it’s bones placed/closely weighted as the low poly hand does so that the hand correctly stretches to fit the user’s real hand data. If you don’t mind some tip misalignment or your model doesn’t support deformation (e.g. ue4 mannequin model) then untick this option and it will apply rotations only to the hand which works far more universally.
For hand chirality, are you using this attached to a VR headset or is it e.g. on a table facing up? If it’s the latter, you’ll need to call SetLeapMode (https://.com/leapmotion/leapunreal#set-leap-mode) in e.g. your begin play and set it to LEAP_MODE_DESKTOP this should ensure the tracking software expects the correct chirality based on it’s orientation. The example LeapDesktopActor has this call, open the blueprint to see where the calls are done.