If I install Visual Studio 2015 as an Administrator, windowslib detects the install and emulators fine. If I switch over to a normal user account that can run Visual Studio but hasn't yet - it does not detect Visual Studio. Once I run it one time, it will generate the registry key we're searching for and find the VS install - but will not find the emulators.
It looks like it's because we're searching for a registry key ending in "_Config" which is generated by the install for the installing user, or on first run for other users. I'm not sure we need that registry entry for the most important data needed by the detection code. Specifically, it seems that we can grab the install directory via another registry key that's always there for VS 2015+.
HKLM\Software\Wow6432Node\Microsoft\VisualStudio\14.0
For older versions, I don't think it contains the data we need.