I found the reason. I missed to specify the directory in '/opt/.filetool.lst'. I only added the files...
If I explicitly specify the directory '/usr/local/etc/test' in '/opt/.filetool.lst' it does restore ownership correctly.
If I only specify the file(s) '/usr/local/etc/test/test.cfg' in '/opt/.filetool.lst' it does not restore ownership of '/usr/local/etc/test'.
From extracting '/mnt/vda1/tce/mydata.tgz' it appears to store also the ownership of '/usr/local/etc/test', but it doesn't...
Steps to reproduce the issue I ran into:
# Using TCL-14.0 x86 (expect same on x86_64 and also on TCL-15.0)
# verify logged in as tc (expect uid=tc, gid=staff)
id
sudo mkdir /usr/local/etc/test
sudo chown -R tc:staff /usr/local/etc/test
# verify directory created with owner tc:staff
ls -la /usr/local/etc/
touch /usr/local/etc/test/test.cfg
# verify file created with owner tc:staff
ls -la /usr/local/etc/test/
#echo usr/local/etc/test >> /opt/.filetool.lst
echo usr/local/etc/test/test.cfg >> /opt/.filetool.lst
filetool.sh -b
mkdir /tmp/test
tar xzf /mnt/vda1/tce/mydata.tgz -C /tmp/test
tce-load -wi tree
tree -pug /tmp/test
# confirm from the 'tree' output ownership of '/usr/local/etc/test' to be tc:staff
sudo reboot
ls -la /usr/local/etc/