FWIW - I've used calibre's Export/Import to move calibre from MacOS to Windows more than once, without any issues.
However, I used a portable HDD freshly formatted as exFat on the Macs as the transfer media. Would have been calibre versions 5 and 6, and Windows 10, but I can't recall Mac OS versions.
I've done the same for Windows to MacOS using the same portable drive freshly formatted as exFat on the Mac.
BR
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