There should be an installer log in the same folder as the installer, it might have the same name as the installer or just be installer.log... please provide it
I'm unable to replicate this issue on the version you indicated, however this was a known bug on some previous versions and has since been fixed.
Are you sure you got the version correct?
Do you not see the public static fields in ForgeConfig that are holding the config instances, and the public fields in those config instances you can .get()?
The registry entries have nothing to do with the mod that adds this login screen
Please provide debug.log (more info on where it is and how to provide it in my signature below, just expand the spoiler)