As to the Me410 – as the sole survivor there should be no question that it belongs in the place of its construction .

http://airandspace.si.edu/collections/artifact.cfm?object=nasm_A19600329000
https://www.flickr.com/photos/71709766@N00/400080432

Not quite the sole survivor!
I wouldn’t necessarily mind the Me410 going back to Germany, but it had a pretty major role in combatting the British and US strategic bomber campaign – so it has a good deal more relevance than the Ki-100.