@Boyan-Biandov I also have basically re-used my Win7 unattend, though I did run it through the Win10 SIM to validate it. The only place I put it is in C:\Windows\Systems32\Sysprep folder. However, I have had the “Windows could not parse…” error and in looking at the setuperr.log in C:\Windows\Panther\UnattendGC folder (this one is different than the setuperr.log in C:\Windows\Panther, I don’t recall how though), it pointed me in the general direction of the <ProductKey>xxx</ProductKey> entry in “Specialize” pass. I ended up removing all product key entries and don’t have the error anymore. I have never really used audit mode, I just enter product key during installation and run “c:\Windows\System32\SLMGR.VBS” /ato" to re-activate after imaging (in setupcomplete.cmd). Good luck!
Edit: Forgot to mention that it always seemed to me that the unattend in C:\Windows\Panther was a post-sysprep record with all the sensitive data removed from the file by Windows as it processed it. I never before ran into any instructions to put it both places so I never have. Now if someone could tell me how they make the Win10 Default User profile keep the pinned icons on the taskbar I’d be the happiest camper alive.