If the installer can't find the JVM
then things could go wrong.
When I install Tomcat on the 64-bit system using the wizard I had to tell the installer the location of the 32-bit JRE.
Doing a silent install fails since it can't find the JRE.
I then installed the 64-bit JRE. The Tomcat installer picked that right up.
You'd have to check the nsis script to see
how JVM detection is done