Look for setupact.log and setuperr.log files under the following paths:
C:\Windows\Panther
C:\Windows\Panther\UnattendGC
C:\Windows\System32\sysprep\Panther
Additional log from this post: https://forums.fogproject.org/post/96860
But now, i know all sysprep logs … :
cbs.log
setup.etl
session.xml
setupact.log in Windows folder
setupact.log in Windows\Panther folder
setupact.log in Windows\Panther\unattendGC folder
setupapt.dev in Windows\inf
setupapt.offline in Windows\inf
setuperr in Windows\Panther …