had the rare case of a folder created by whatever process folder named cd C:\Users\user\AppData\Local\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\deep\deep\down
which made both takeown /f "C:\Users\user" /S HOSTNAME /u domain\username /r /d J
and icacls "C:\Users\user" /setowner "domain\username" /T /C
(was trial and error icacls, see at bottom what is the right approach once buried folder is removed) terminate prematurely due to the path length barrier.
cd C:\Users\user\AppData\Local\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\Anwendungsdaten\deep\deep\down
$path = (dir .\subfolder_in_buried_folder\anyfile_therein).FullName
$object = New-Object -ComObject Scripting.FileSystemObject
$output = $object.GetFile($path)
Write-Host "`n`n The short path of this directory is" $output.shortpath.trim("anyfile_therein")