Hi,
in my lab I was able to change it remote syslog IP in following VCSA config file:
/etc/vmware-syslog/syslog.conf
and afterwards, needed to restart rsyslog:
systemctl restart rsyslog
I am not quite sure for Powershell but try looking into something like "sed" if you're looking to replace/update lines with BASH script.
However, I don't know if that's supported, so it would be better to ask support before making changes in a production environment.