(i hope this board is a decent choice...)
First of all: thanks to the R&D folks for providing us with config_system! It's a huge help for automation, and I know you know that already. 🙂  Thanks!
 
I seem to have found a bit of a flaw in config_system.  I did have a minor error in syntax when I generated the FTW config (yes my fault).  However, the dry-run check did not detect the syntax error properly.
 
My config was:
 
# Install Security Gateway. 
install_security_gw=" true "
 
This was generated from my own Ansbile Jinja2 template, and I know I had the error there.  Notice the spaces inside the quotes.  Since dry-run didn't detect the error, my playbook continued to execute and ran the task to run config_system with the config file.
 
After 30 minutes of no progress, everything timed out and died.  config_system never really did anything.  I re-ran it manually, and it sat at "Configuring products":
[Expert@gaia_demo:0]#  /usr/bin/config_system  -f /home/admin/gaia.ftw.config 
dos2unix: converting file /home/admin/gaia.ftw.config to Unix format ...
Validating configuration file:	Done
Configuring OS parameters:	Done
Configuring products:		-
 
It was still running in the process-list:
  863 ?        S      0:00      \_ /opt/CPsuite-R80.40/fw1/Python/bin/python3 /var/tmp/ansible-tmp-1651184043.6572037-2564807-184818913965851/AnsiballZ_command.py
  865 ?        S      0:01          \_ /bin/bash /usr/bin/config_system -f /home/admin/gaia.ftw.config
 
I then looked at the config file for sanity and saw the erroneous spaces.  I fixed the config, ran it again, and it finished in just a few minutes (as expected)!  That's when I realized this was the error. I found and fixed my Jinja2 template and now it all works.  I understand this was "my fault", but it does show that there is a syntax-processing and some kind of run-time error in config_system.  Oops.
 
The system was a fresh-install R80.40 (no Jumbo HFA yet; that was coming next in my playbook after the reboot once the products were configured; yes I updated CPDA beforehand, too).
 
I hope this is enough to have someone take a look internally.  Take care!