Hi,
I have no experience with NSIS but just did this as a silent install with Automate Ultimate 11 by doing the following
IN a CMD RUN
automate_plus_ultimate_11_x64.exe /b"c:\temp\automate"
This will extract the MSI from the EXE to c:\temp\automate.
The I ran the below. It is the ADDLOCAL that makes the trick. Could be that Enterprise has different variables. To get these variables I ran the below but without the /QN and ADDLOCAL. Choose the features I wanted and went through the installation. I then looked through the install.log file and searched for the ADDLOCAL part.
msiexec.exe /i "Automate Plus and Ultimate 11 (x64).msi" /QN ADDLOCAL=Common,Dev_Tools,Runtime /L* C:\temp\automate\install.log
The support told me it was not supported but I works.
Good luck