I agree with Eivind Bakkestuen.
If you execute original installer with command-line parameters, for example:
ecostruxure_power_design_e.exe" /log=ecostruxure_power_design_e.txt /silent
If you look in the log-file, you will see the "Got EAbort exception."
Before it's written: "Failed to proceed to next wizard page; aborting."
So, it means that it checks if anything if chosen in the "country page". But they did not add any command line parameter to change it.
To be sure I also checked the "CompiledCode", if anything is hidden there, but I can't found anything more that that:

So, you can extract original installer and include extracted files in your installer, or you can ask them to add command-line parameter to change it (as
Eivind Bakkestuen wrote). Anyway, you can repack their installer, but you will lost original certificate...