Oboe, I don't think they did that so much with the Japanese planes. At least I've not read of them doing anything like that. Why train on a fixed-gear Ki-27 over hostile territory when you can train in a A6M5 or something else?
I'm not specifically saying I don't think there was a kill recorded. I'm saying I don't think the story happened the way it is claimed. And because the CLAIM itself is faulty the entire kill report is suspect until all the confusion is cleared up.
Now if there were actual records supporting it, fine it's a quirk that in 1945 a plane from 1939 was shot down. Call it a time wormhole, whatever. However without actual support, it's not likely.
If it's a simple matter of "Oh, it wasn't a Ki-27, it was a fill-in-the-blank" then it changes nothing in these posts. The kill is still valid. If on the other hand it's a confusion of multiple reports and the kill that was made was actually from 1939? Or perhaps it's like the 2x20mm cowl gun myth on the 109K4, some typo or misprint that is mistranslated several times and not based in reality?
Again, you can't be sure until it's cleared up. That's why I say the burden is to support the claim rather than to debunk it. Otherwise I would take "normal" kills at mostly face value. Spitfire kills a He162, for example. Both planes in the same area at same time, perfectly plausible.