First: Thanks for Carbon - it is really amazing!
Install-Junction.ps1 file checks for existing files by using:
if( -not (Test-Path -Path $Target -PathType Container) )
This will fail when the $Target contains special chars such as . You can fix this by using the -LiteralPath arg:
if( -not (Test-Path -LiteralPath -Path $Target -PathType Container) )
I can't see a good reason not to use the literal path in this scenario - creating junctions using wildcards isn't really an option.