Still they had a few prototypes from the plans they did get didn't they ?
Nakajima Kikka ?
Mitsubishi J8M Shusui ?
R2Y Kein ?
Shinden ?
and had some underground facilities to build them too, didn't they ? Dug into mountains ?

They could've caused a lot of "grief" had they got the plans earlier, got them to fly & return, secured the necessary materials earlier, had fuel/weaponry left when they were needed over their homeland.

I know, a lot of "if" s.

In the end, it wont change the outcome. Troublesome to ponder though.

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